Bestiarium of the future - Fishes
In this section descriptions of various animals and plants, which could live on the Earth in Neocene epoch. The section will be supplemented as new ideas about possible ways of evolution of life will appear. If readers will not find here any species placed here earlier, it means that it is a reason to search for a new chapter in English version of "The Neocene Project".

Eastern lamprey (Petromyzon floridana)
Order: Lampreys (Petromyzontiformes)
Family: Northern lampreys (Petromyzontidae)
Habitat: fresh, brackish and coastal sea waters of the Atlantic coast of North America.

Picture by Ilya

In due course of evolution, it often happens that in the struggle for existence, not the most complex organism wins, but a much simpler one, up to unicellular ones. Hagfishes and lampreys, the last representatives of jawless fishes known since the Early Paleozoic, have experienced a variety of ecological and climatic cataclysms, including Permo-Triassic, Cretaceous-Paleogene and Holocene-Neocene extinction events. People, before they disappeared from the face of the Earth, exterminated many species of other living beings, but lampreys remained.
The Eastern lamprey is a descendant of the sea lamprey (Petromyzon marinus) of the Holocene epoch. The lack of specialization in the anatomy and lifestyle, as well as the ability to live in both sea and fresh water, allowed it to survive the era of anthropogenic pressure and the next Ice Age, and later give rise to several new species in Neocene. Eastern lamprey is a rather large jawless fish, reaching 35-42 cm in length, but tail makes about a half of this length: it is not only large, but also strong, equipped with a primitive skin fin. It allows the lamprey to make sudden rushes at prey.
Eastern lamprey is a predator and prefers to hunt from ambush: its brownish-gray color (the belly is slightly lighter than the back) allows it to hide at the bottom among silt, rocks, coastal and underwater vegetation until the prey approaches the attack distance. Attacking its prey, eastern lamprey clings to the body of the prey and tightly attaches to it, scraping the covers of prey’s body with its tongue and inflicting a rather deep wound. While feeding, it swallows blood, shredded meat and entrails until it is sated and falls off, like a leech. Usually, eastern lamprey hunts fish and large amphibians, less often it attacks waterfowl, clinging to their legs. But it especially likes to eat crayfishes and crabs: its mouth sucker and tongue are quite capable of making a hole even in shells of these crustaceans, and it eats them out clean, leaving after its meal only a perforated shell.
In case of danger, this animal hides in the ground, burying itself in it with intense movements of the body.
This lamprey itself does not have a lot of enemies – mostly these are various birds (herons and ibises), less often fishes that eat the juveniles of this lamprey in large amounts. Therefore, like the eels of the human era and in contrast to almost all its relatives, the eastern lamprey spawns in seawater, but not far from the coast. This species prefers to breed in places where seawater is largely freshened by rivers and there are vast areas of sandy bottom, so the largest populations of eastern lamprey are found in rivers flowing into the Gulf of Mexico and forming vast deltas. In the courtship dress, the coloration of this lamprey is olive-green with a yellowish-white belly. Fertility is up to 70 thousand small eggs, which are spawned in the thick of underwater plants. The larvae of the eastern lamprey are typical ammocetes, like in lampreys of the Holocene epoch, and they feed by filtering water. They usually bury themselves in the sand, exposing only their heads and turning their mouths against the current. Being disturbed, they quickly hide in the ground and dig themselves deep. The ammocete larvae of the eastern lamprey grow quickly, and after 5-6 months they already undergo metamorphosis and switch to a predatory lifestyle. At this time, they leave the coast and migrate to fresh waters more suitable for them.
The maximum lifespan of the eastern lamprey is 14-15 years, but as a rule they die much earlier.

This animal species was discovered by Bhut, the forum member.

Flat-headed lamprey (Platymyzon symbioticus)
Order: Lampreys (Petromyzontiformes)
Family: Northern lampreys (Petromyzontidae)
Habitat: Mishe-Nama Lake, facultative symbiote of large aquatic animals.

Picture by Lyagushka

Jawless fishes in the modern world represent a group that stays in the “shadow” of more numerous and diverse fishes. The heyday of the jawless fishes passed in the Paleozoic, and these animals occupy only a few ecological niches. In North America, these animals had got a chance to prove themselves when Hudson Bay turned into a vast Mishe-Nama Lake with almost fresh water. Numerous descendants of marine animals live in this lake, and among them there is a descendant of the sea lamprey Petromyzon marinus, which spends its entire development cycle in fresh water. It is flat-headed lamprey – a species that occupies a special place in the ecosystem of the lake.
This lamprey species lives on the surface of bodies of large fishes living in the lake, and is a kind of analogue of the remora. Attaching itself with a mouth sucker, flat-headed lamprey keeps on the body of fish for a long time, clearly preferring the large local oshadagea rays (Oshadagea aquilla). Adults of this species grow to a length of 10-13 cm. They have a wider body compared to free-living lamprey species, which is also flattened dorsoventrally in the anterior part. The oral sucker of this lamprey is strong, equipped with elastic edges and numerous small corneous teeth. Due to the peculiarities of the lifestyle, this species also has reduced eyes. The body color is brown, white on the throat and in the front of the belly. Fins are short and relatively small.
Flat-headed lamprey attaches to the skin of fish and hangs, from time to time swimming from one place to another. It scrapes the upper layer of the skin of the host fish, cleaning off its parasites and dead tissue areas. Also, the flat-headed lamprey likes to scrape wounds on the body of the host animal, thereby interfering with their healing, and feeds on oozing blood. Usually these animals do not bother the ray, but if the ray feels pain, it can drive off part of the lampreys, rubbing its belly against the backs of congeners or accelerating sharply and jumping out of the water.
This lamprey species is territorial – a strictly defined number of individuals can coexist on one host fish. A group of lampreys protects their stingray individual from strangers, driving off their congeners trying to settle there. But they also keep some distance from each other. If a large host fish is not found, the flat-headed lamprey can live independently for some time, or it tries to attach itself to other large aquatic animals, for example, to dwarf gannetwhales, but detaches itself from them when these birds get out of the water. Free-living individuals keep at the rocky areas of the bottom with the current, feeding on small sedentary animals.
This species spawns once in a lifetime, in the spring. Before spawning, the digestive tract degrades, and the fins increase. Animals leave their hosts and move to the mouths of rivers flowing into the lake. The female spawns up to 50 thousand eggs, burying them in the sand; after spawning, adults die. The ammocoete larva lives in the coastal zone and in the river estuaries in deposits of fine-grained sand with silt, and feeds on bacteria and organic matter, swallowing silt. The duration of the larval stage is up to 5 years; after metamorphosis it lives for 2 years.

Floridian big-tongued lamprey (Glossolampetra heliciphaga)
Order: Lampreys (Petromyzontiformes)
Family: Northern lampreys (Petromyzontidae)
Habitat: Florida, coast of Gulf of Mexico, Cuba and Great Antigua.
During the ice age at the boundary of the Holocene and Neocene the habitats of many representatives of cold-water flora and fauna extended further from the poles into the lower latitudes. At the end of the ice age the fates of species distributed during glaciation have developed indifferent ways: some retreated to the poles and became extinct in warmer climates, while others remained in the separate “refuges” of mountain ranges, while others have adapted to the warming and have become one of the components of the new subtropical or even tropical flora and fauna. One species of a small group of lampreys represents this kind of polar component in the tropical fauna of central and southern North America. This species, the Floridian big-tongued lamprey, flourishes thanks to an unusual feeding specialization.
The Floridian big-tongued lamprey is a small animal: the body length of an adult is about 15 cm. The mouth of the lamprey is a soft, round sucker ring with rows of small teeth. Also at this species there is a powerful tongue with large hooked corneous teeth, capable of extending far ahead of his mouth. This is due to the nature of the animal’s food: the Floridian big-tongued lamprey feeds on snails. It sticks its mouth to the snail, expands its mouth over the mouth of the shell, and deeply thrusts its tongue into the shell, and in one motion hooks and pulls the body of the mollusk out of its shell. After this the snail is swallowed whole and the shell is left intact. This species does not stick to living fish and only occasionally scrapes the meat of dead animals.
Unlike many lampreys, the Floridian big-tongued lamprey is colored quite vividly: on a pale yellow background brown spots of irregular shape merge into traverse bands separated by areas without spots. On fins small black specks are scattered.
Usually this animal burrows among plants or sunken leaves. The Floridian big-tongued lamprey shows the most activity at dusk. This species inhabits fresh and marine waters, easily withstanding considerable desalination. In the mangroves there are large individuals up to 20 cm long. With the ability to live in seawater this species is widely spread throughout the tropical waters of southern North America and the Caribbean.
Reproduction of the Floridian big-tongued lamprey occurs in fresh water. Because of this small islands, where there are only few rivers productive enough, represent a barrier to the expansion of this species into South America. Before spawning the coloration of lampreys greatly changes: spots on the body merge into distinct transverse bands, the back darkens and a distinct black border appears on the fins. The lampreys stop feeding and their bowels begin to degenerate. Adults ascend the rivers and spawn in areas with soft ground and slow flow. The larval stage lasts up to 5 years. The ammocoetes eat mud and the rotting remains of small animals.

Translated by FanboyPhilosopher

Long-wattled ghost shark (Caecorectolobus cirrhosissimus)
Order: Wobbegongs (Orectolobiformes)
Family: Carpet sharks (Orectolobidae)
Habitat: Pacific Ocean, depth about 1500 – 2000 meters.

Picture by Timothy Morris, colorization by Alexander Smyslov

Sharks are highly adaptive creatures: this group of fishes is known from Devonian, having proved thus the abilities to adapt to various changes of environment. Opinion that sharks do not evolve till their history is deeply wrong. Various species, families and orders of these fishes replaced each other as regularly, as groups of sea mammals, for example. From most ancient times sharks aspired to take a place of supreme predators of ecosystems. It was possible to them for many times, but sharks had reached especial success in Cenozoic when requiem and mackerel sharks, the top of evolution of sharks, had appeared. The place at top of food pyramid is honourable, but too risky – at ecological crisis predators die out at first. At the boundary of Holocene and Neocene “charismatic” pelagic sharks dwelt at ocean had disappeared – schools of pelagic fishes served as food to them and their catch had died out. Their populations undermined by chasing of people gradually degraded. To early Neocene at the planet mainly medium-sized bottom-dwelling sharks survived. And they had given in Neocene a new wave of speciation. The majority of Neocene sharks are descendants of these species.
After ecological crisis and extinction of pelagic organisms sharks descending from shallow-water species developed the oceans anew. Among them there were species had mastered polar waters of Arctic Ocean and Subantarctic. And some sharks had started to storm ocean depths. Deep-water fauna depended on efficiency of ecosystems of top layers of water had suffered huge damage till the time of “plankton accident” at the boundary of epochs, therefore at early Neocene deep-water ecosystems had started to form practically from zero.
Among sharks occupied depths of ocean there is one descendant of carpet sharks, whose ancestors lived in shallow waters earlier. Obviously, ancestors of this fish had “moved down” to depths of ocean along the continental slope (obviously, somewhere in area of Australia or Indonesia). Therefrom this fish had passed to pelagic habit to life already as deep-water animal. Hence of fantastical appearance this fish named ghost shark. The length of this fish is about 2 meters; tail fin with much lengthened top blade located almost horizontally makes about one third of general length.
This fish lives in depths where change of day and night is not felt at all – at the depth over thousand meters. Colouring of skin of ghost shark is unicolor light grey; that’s why fish looks “belongig to the beyond”. As against overwhelming majority of Neocene sharks it is completely blind fish – even a sign of eyes is not remained from outside. Eyes are functionally replaced with another “secret weapon” especially advanced at sharks – instead of them organs of lateral line are used for orientation in water. Ghost shark has flat head, lengthened body and rather short fins. At this fish there are two back fins, on each back fin there is hollow corneous spike connected with poisonous gland. This is the main protective adaptation against deepwater predators: sometimes these sharks are attacked by squids and their own larger congeners.
Similarly to all carpet sharks the ghost shark has many skin outgrowths at the edge of muzzle. This inheritance from carpet sharks of shallow water habitats earlier serving for masking had got other function in gloom of depths, much more important for survival: very much advanced outgrowths on head contain branches of lateral line, and fish orientates with their help. Outgrowths on muzzle reach the length equal to fish’s head. It has determined the specific name of fish: “cirrhosissimus” means “the most whiskered”. Organs of lateral line located on outgrowths of fish’s head permit to trace the slightest changes of electric field surrounding fish, meaning presence of other live creatures.
Besides long-wattled ghost shark there is very keen sense of smell: it has large chinky nostrils.
This shark is slow: the most part of time it passively floats in thickness of water, tracking down other fishes and various pelagic invertebrates – squids and octopuses. Its catch not always differs in speed; therefore it may be easily caught even by such blind and slowly moving predator. Long-wattled ghost shark is able to catch fast catch, making short sharp throws. This fish eats basically fishes and squids having soft and flabby body consistence. Therefore its teeth have not cutting or crushing, but thrusting type – they are rather thin, awl-like and slightly bent. With the help of such teeth it is easy to catch slippery and soft-bodied prey. Having an opportunity, long-wattled ghost shark sometimes eats carrion – corpses of fishes and large sea animals immersed to the bottom. Eating carrion, the fish seizes sticking up parts of carcass and sharply turns, trying to tear off a piece. But more often this shark is interested not in carcass, but in animals coming to feed at it.
In typical case sharks lay large eggs from which the posterity hatches after rather long time. For the pelagic species living above the big depths, such vital strategy is unacceptable: females should make migrations to the continental slope to hatch posterity or to lay eggs right in water where they will fall to depth and can not develop there. The smaller number of sharks is live-bearing species, and long-wattled ghost shark belongs to their number. Pairing at this species occurs at any time of year – in ocean depths seasonal change are not expressed. Male is a little bit smaller than female (its length is about 170 cm), and has advanced copulating organs on abdominal fins. It has keen sense of smell and searches for the female ready to pairing by smell. Having found it, male catches it up and slightly compresses by jaws her back fin, stopping the female and showing to it readiness to copulation. As a rule, deep-water animals differ in small intensity of metabolism processes. For this reason pregnancy at this shark lasts for very long time: about 15 months. Fertility of long-wattled ghost shark is very small: the female gives rise only to two young fishes. But the newborn shark of this species is about 60 cm long at once is able to eat independently and due to the size avoids the fate to be eaten. After birth of posterity the female picks up and eats egg shells. In some days after birth of posterity the female is ready to reproduction again. The young fish reaches length of 1.5 m at the age of 10 – 13 years. In same time it becomes able to breeding. Survival rate at young long-wattled ghost sharks is very high. It partly compensates the low reproduction rate: for all life the female gives birth to no more than two tens of young ones.

Rhino shark (Brachyselache pseudokurina)
Order: Wobbegongs (Orectolobiformes)
Family: Wobbegongs (Orectolobidae)
Habitat: temperate and warm waters of the southern hemisphere – the shores of New Zealand, Meganesia and nearby islands.
Wobbegong sharks were among the most atypical sharks of the Holocene; they preferred not to chase prey in the water column, but to lie on the bottom and wait for the prey to come within attack distance of them. Life in coastal waters, less affected during the global ecological crisis at the turn of Holocene and Neocene, allowed them to survive and give rise to new species.
Rhino shark is one of the descendants of the survived benthic species. In its appearance, it vaguely resembles a goblin shark (Mitsukurina) of the Holocene epoch – because of the elongated snout resembling a horn. But while goblin shark lived at great depths and had a rather loose constitution, the rhino shark, on the contrary, is relatively small in size (individuals exceeding 2 meters in length are very rare), of strong build, with well-developed musculature. Its unpaired fins are small, used mainly for turns (this fish is not too maneuverable), but the tail is quite large and strong. The fish is capable of making sudden rushes for prey.
Like the false swordfishes from among teleost fishes of Neocene, rhino shark attacks its prey and delivers it a stunning blow with its snout, but unlike the false swordfishes, the rhino shark is a bottom-dwelling fish species and prefers to attack from ambush. Ampullae of Lorenzini allow it to feel the approach of prey from afar, and the rhino shark either hides or uses environmental objects to sneak up on prey. Unlike most sharks, the rhino shark is able to change the color of its skin to blend in with the environment: among underwater rocks, it is gray, brown or reddish; among algae or reefs, it has a mottled pattern, and on the sandy bottom it is colored to match the color of the local sand, remaining inconspicuous to others until the very last moment, when it makes a rush and delivers a stunning blow to the prey. However, the change of color takes some time: it takes about a day to the shark to get a suitable disguise.
The brain of rhino shark is surrounded by a shock-absorbing layer of fat and a powerful cranium – unlike most other cartilaginous fish, the cartilage of a rhino shark is highly calcified. It is stiff and rigid, especially on the snout, which allows this fish to stun prey.
The prey of the rhino shark includes large fishes, young turtles, as well as young sea-dwelling sharkodiles.
Despite the successful lifestyle, the rhino shark itself turns out to be prey to larger predators, including other sharks, and to adult sharkodile individuals in the north of its range.
Rhino shark is an oviparous fish species; in warm waters it is ready to mate all year round, in more temperate southern waters the mating season falls at the end of winter. Females of this species lay about a dozen large eggs. Incubation lasts up to 10 months; young shark has a length of about 30-35 cm, and is immediately able to feed on invertebrates.
Sexual maturity comes at a length of 1.2 m in females and 1 m in males – at the age of about 8 years. Life expectancy can reach 40 years, but most young fishes die before this period.

This fish species was discovered by Bhut, the forum member.

Shovel-headed shark (Brachyselache electricus)
Order: Wobbegongs (Orectolobiformes)
Family: Wobbegongs (Orectolobidae)
Habitat: temperate and warm waters of the southern hemisphere – south of South America, Tierra del Fuego, Subantarctic Islands.
At the turn of Holocene and Neocene, the mass extinction of planktonic organisms (the so-called “plankton catastrophe”) caused the disappearance of a significant number of open ocean fish, including mackerel sharks. Shallow water bottom-dwelling shark species survived the “plankton catastrophe” much more successfully, and in Neocene began to develop new ecological niches, getting new adaptations for survival. Among the surviving groups of sharks, there were wobbegong sharks, and in the Neocene very peculiar forms evolved among them. One of the species with an unusual appearance is the shovel-headed shark from the seas of the southern hemisphere.
The appearance of the shovel-headed shark is easily recognizable: its head is somewhat elongated forward and strongly expanded at the level of the eyes. Unlike most other sharks, this species has poor eyesight. Next to the eyes are the nostrils: they are quite large (larger than the eyes), slit-shaped, and equipped with valves that close them when this shark gets its food: small and medium-sized benthic fish, crustaceans and other invertebrates.
Despite the name, this shark does not dig up the bottom using its head like a shovel: this head shape allows it to carry a whole network of sensitive ampullae of Lorenzini that sense the electrical impulses of animals hiding at the bottom. Also, sensitive nostrils allow it to find hidden animals by smell.
Such food specialization and benthic lifestyle have led to the fact that the shovel-headed shark is a bad swimmer. It still retains a rather recognizeable “shark” appearance, but it lacks a dorsal fin (only a small skin fold remains from it), and the lower lobe on the tail fin is greatly reduced. This fish swims relatively slowly, tilting its body to the bottom at an angle of almost 45 degrees to make it easier to search and catch prey. At this time, the mouth is open, and the head moves almost parallel to the bottom surface. The skin of this species is colored almost exactly like the color of the sea bottom – yellowish, grayish, brown – with differences in different populations; the belly is slightly lighter than the back. This shark keeps at depths from 2-3 to 50 meters, in winter in the southern part of its range it hides at a greater depth and does not feed.
Shovel-headed shark is a small fish according to shark standards: its average length is slightly more than 1 meter; the maximum is no more than 2 meters. The body constitution is rather gracile; shovel-headed shark often falls prey to large cephalopods and sharks of other species. It is able to swim fast for a very short time – only for some minutes, after which it must rest for a long time, swimming slowly or lying in a shelter.
Shovel-headed shark is an oviparous fish species; in the north of its range, it is ready to mate all year round, in more temperate southern waters the mating season falls at the end of winter, but in any case, the females of this species lay at least a dozen large eggs covered with a dense corneous shell, and hide them in secluded places – in cracks between stones and in the thickets of underwater grasses. Incubation lasts up to 11-12 months. A young shark about 20-25 cm long is similar in body and head shape to adults, differing from them only in contrasting color – a pattern of black transverse stripes on a yellowish-brown background.
Sexual maturity comes at a length of 1 m in females and 75-80 cm in males – at the age of about 7-8 years. Life expectancy is no more than 50 years, but most sharks die before this period.

This fish species was discovered by Bhut, the forum member.

Mangrove snark (Anguilloselache snark)
Order: Wobbegongs (Orectolobiformes)
Family: Nurse sharks (Ginglymostomatidae)
Habitat: Indo-Pacific, coastal waters in tropical latitudes, mangroves.

Picture by Sauron from FurNation

In Neocene, the fauna of coastal marine waters has undergone significant changes. The global ecological crisis and human activity have caused the extinction of many species of reef-building corals, mainly of species with a hard calcareous skeleton. Following the corals, numerous species of fishes and invertebrates that depended on corals for their lives died out. And their disappearance caused the extinction of predators. The fauna of mangroves, which were destroyed during the epoch of maximum human domination, also suffered.
After the disappearance of mankind, reef ecosystems and mangroves gradually recovered to the extent that a set of surviving species allowed them to do so. At the reefs and in the mangroves of the Neocene, there are a variety of predators that have evolved from the few species that survived the ecological crisis. A characteristic group of predatory fish of these habitats is snark genus of long-bodied eel-like sharks that live at the bottom and in thickets. The name of these fish comes from words “snake” and “shark”. These fishes descended from nurse sharks (Ginglymostoma) of the Holocene epoch.
Snarks differ from other sharks by a very thin and elongated eel-like body, the length of which exceeds the depth by tens of times. The body length varies greatly in different species – the smallest species does not exceed one meter in length, and the largest one grows up to 3 meters. The upper lobe of the snark’s tail is horizontal, and the lower lobe is very small. Because of this feature, the snark’s tail looks more like a tail of an eel, rather than of a shark. Snark has a shortened head with an almost terminal mouth, at the corners of which two fleshy wattles grow, being organs of touch and chemical sense. Snarks also have a well-developed sense of smell; large nostrils are equipped with small lobe-shaped outgrowths along their posterior edges. The eyes of snarks are relatively small and equipped with a developed blinking membrane. They are located at the top of the head.
At the beginning of the dorsal fin of snark, a large corneous spike grows. It can partially retract or, on the contrary, protrude from the fin due to the system of annular and longitudinal muscles surrounding its base. Many species of snarks live in burrows and with the help of such spike they fix themselves in their shelters.
The paired fins of snarks are short and rounded. These fish are slow swimmers. They are able to catch prey with a short, fast rush, but they swim very slowly over long distances. Snark reluctantly leaves the chosen shelter and prefers to stay in it while there is an opportunity for this. The fish that has left the shelter swims, wriggling with its whole body, like an eel.
Snarks live mostly in seawater, but some species do not avoid lower salinity areas of mangroves, and even go up the river. These sharks are exceptionally viviparous. The female gives birth once a year to two large juveniles similar to an adult one, but often having a different color pattern.
Mangrove snark is one of the largest species of this group: its body length reaches two and a half meters. It has a typical eel-shaped body and inhabits mangroves. The body color of this fish is brown with small white spots and “veins” forming a marble pattern on the sides of this fish. Throat and chest between the fins are white. This species feeds on crabs and mollusks, the shells of which are crushed by its strong teeth. In search of food, the mangrove snark often digs in the mud.
Young individuals of the mangrove snark are sedentary. Hiding from enemies, they keep among the roots of mangrove trees, wrapping their pectoral and pelvic fins around them, and remain motionless for several hours in a row. At low tide, young sharks burrow into the fallen foliage of mangrove trees. Their coloration is gray-brown with several transverse “scars” of a darker color; with age, a marble pattern characteristic of adults appears. Young mangrove snarks feed mainly on mollusks, later they begin to hunt crustaceans.

Picture by Sauron from FurNation

Sand snark (Anguilloselache psammobius) belongs to the small representatives of the genus and lives only in seawater. It is found in reefs in the coastal waters of Indonesia, Jakarta Coast and the northern tip of Meganesia. The length of this fish does not exceed 75 cm, but usually is less. The color is grayish-white with variations from bluish-gray or yellowish to snow-white. The belly is always white. The spike in the dorsal fin is unable to be retracted, but it is poisonous. This species prefers to lie in wait for prey by burying itself in the sand. In this regard, the eyes of this fish are shifted to the upper part of the head, and the spiracles are large. In a fish buried in the sand, only the upper part of the head, the spike of its dorsal fin and the tip of the tail are exposed to the outside. This species feeds on shrimp and small crabs. Juveniles of this species have a lead-gray color and hide in crevices and cracks of the reef, moving to sandy areas with age and changing their color to a lighter one.
Barbed snark (Anguilloselache barbatus) is an exclusively marine inhabitant, not found in fresh water. This species is about one and a half meters long and has a rusty-red color with spots of dark red and white, forming an irregular pattern. Such coloration helps the barbed snark to hide in the reef among algae and sedentary animals. Camouflage coloring is complemented by skin outgrowths along the edges of the mouth and above the eyes. This species is omnivorous, and equally eager to catch fish and invertebrates. Young fishes are colored brighter than adults, and their spots form a semblance of a cross-striped pattern. With age, the rusty-red color begins to prevail in the coloration of this fish, and the spots of other colors become smaller. The barbed snark is common in coastal areas of East and Southeast Asia.
Moray snark (Anguilloselache muraenoides) is the largest species of the genus, up to three meters long. It is an active predator feeding almost exclusively on fish, but can catch seabirds swimming in shallow water. Often this species enters estuaries and rivers, where ducks and small herons become its prey. This fish deals with large prey like a snake – it wraps its body rings around the prey and drags it under water. However, unlike snakes, the moray snark is able to bite off pieces of prey and swallows it piece by piece. The adult moray snark has a cross-striped pattern – brown stripes on a yellow background; the back is darker than the belly. Young individuals of this species have a mottled coloration; spots merge into stripes with age. Its range includes Southeast Asia and Jakarta Coast.

Picture by Alexander Smyslov

River snark (Anguilloselache fluviatilis) is a true freshwater snark species rarely found in the sea. It inhabits the rivers of Southeast Asia, Jakarta Coast and nearby islands. The body length of this species is up to one and a half meters, rarely bigger; the color is greenish-gray with a darker back, a white spot on the lower jaw and an indistinct marble pattern on the sides. River snark is an ambush predator that preys on small fish and crustaceans. Usually these fishes arrange shelters in thickets of aquatic plants. During the rainy season, these fishes can migrate to sea and swim in the upper desalinated layer of water, crossing the straits between the islands. This species does not form stable local forms at the islands.

The idea of the existence of this group of fishes was stated by Andrey, the forum member.

Pike shark (Esocisqualus rivularis)
Order: Dog sharks (Squaliformes)
Family: Dog sharks (Squalidae)
Habitat: Asian rivers of Pacific and Arctic Ocean basins.

Picture by Alexander Smyslov

Shark in the river is more exception, rather than rule. Usually these cartilaginous fishes live in sea, though some species of fossil sharks of Paleozoic era were found in river deposits, and in Holocene some species of sharks were known, able to live and breed normally in rivers. Basically such phenomenon was typical in tropical zone of Earth. However in this case occurrence of freshwater species of sharks in northern rivers was quite natural: approach of glacier from the north forced some sea polar species to recede to rivers. This way in the rivers of Eurasia burbot (Lota lota), the freshwater descendant of sea cod fishes, has appeared.
Ancestor of the pike shark is one of sea dog species of Pacific Ocean. Receding to rivers during ice age, they adapted to long existence in fresh water, and then had made very important step: began to breed in rivers, having torn thus connection with salt water of ocean. At floods of rivers these sharks had settled over far inside of continent - in headstreams of rivers of Arctic Ocean basin. Being isolated from ocean, small sea dogs evolved to separate species – pike shark.
Pike shark is rather large fish: its length is up to 2 meters. Though for sea species it is rather mediocre size (frankly speaking), in fresh water of cool rivers of Northeast Asia only few species, capable to be compared to this shark in size, may be found. Body of this fish is very long and thin: the maximal height of it does not exceed 15 cm. Pike shark crowns feeding chain of northern rivers, being in them the original ecological analogue of crocodile.
The shape of pike shark is characteristic for the majority of sharks: pointed snout, inferior mouth, triangular fins and crescent tail. Colouring of body of this fish is striped: on olive-brown background cross light strips pass, breaking to separate spots on head. Head of pike shark is narrow and flat. Teeth are triangular and sharp: the basic food of this shark is medium-sized fishes and crayfishes. Sometimes pike shark eats small mammals got in water, and waterfowl.
This shark has kept a heritage of ancestors – sharp sense of smell and well advanced circuit of bodies of lateral line on head. These adaptations are especially useful at life in the river when water frequently happens muddy. However sight at pike shark also is well advanced: at it there are large yellow eyes with narrow vertical pupils.
By the habits this fish is typical bottom-dwelling predator. This shark spends the most part of time in thickets of plants, having directed by head against current. So it is easier to it to ventilate gills, and fishes and swimming animals, carrying by current, are visible. Colouring helps pike shark to mask.
In case of necessity this shark can swim from one place to another, bending eel-like by all body. But at attack it develops significant speed: up to 60 km per hour during several tens seconds. However in general it is nevertheless rather bad and lazy swimmer. This fish spends winter in deep holes in river channel, having stopped feeding completely. In winter time pike shark lives due to fat had been accumulated in long liver, stretching along all abdominal cavity.
Appetite at the pike shark awakes in spring when day becomes longer, and water gets warm. During floods of rivers when in river many bodies of drown animals float, pike sharks almost completely pass to feeding by carrion. In summertime when river water strongly gets warm, and the contents of oxygen in it decreases, sharks leave shallow tributaries and keep in places with cooler water: at the bottom of river and near underwater springs. In summer this shark hunts at night.
The basic problem of many sea fishes at transition to life in fresh water is the egg development: their eggs may develop only in salt water. Pike shark had avoided this problem by simple way: it is live-bearing fish. Pairing occurs in the beginning of summer, when fishes grow fat and restore forces after winter catalepsy. Males start to chase females, from time to time cautiously biting them to back edge of back fin. Pairing lasts not for long, and takes place in thickness of water.
In oviducts of the female within 10 months simultaneously 2 youngs develop, growing up to 30 cm. They are born in late spring and at once live quite independently, eating small fishes and crustaceans. Colouring of young fishes is more sated and contrast, than at adults. At the sixth – seventh year of life, when the length of young fishes reaches one and half meters, they become able to breeding.
Pike shark yields to pike in longevity: the age limit of this fish can exceed 100 years.

Sea onza (Physelache versicolor)
Order: Dog sharks (Squaliformes)
Family: Giant sharks (Cetoselachidae)
Habitat: Atlantic and Pacific Oceans, tropical areas.
In the age of man, sharks suffered from overfishing and disturbance of the natural balance in marine ecosystems, as well as many other groups of living creatures of the open ocean. After the human disappearance, a serious blow to the remaining species was caused by the “plankton catastrophe” of the late Holocene – early Neocene. Large and numerous small species of these pelagic predators went into oblivion following their prey. The surviving species, however, continued to evolve, and took the dominant place of the supreme predators of the ocean again – although large cephalopods were their competitors. Among the ocean sharks, even giant species have appeared – such as the cachalot shark from the temperate regions of the Atlantic. The second largest shark is the sea onza – its closest relative.
The length of this fish is 14-18 m, and the weight is up to 30-35 tons. The male is larger than the female, and differs from her in color – there is a triangular figure of spots on his head. This shark species resembles the cachalot shark in its proportions: large flat head with a wide mouth makes about a quarter of the total length, and about the same amount is made by an elongated caudal fin with a very long upper lobe that is positioned almost horizontally. The lower lobe of the tail is almost completely absent. The pectoral fins are wide and oval; their bases are shifted upwards, and the fish flaps them like wings when moving. The coloration of the back and sides is black with blurred yellowish spots; throat and belly are yellow.
The eyes of this fish are slightly larger than those of a cachalot shark, and the nostrils have the same tubular structure, providing a continuous flow of water when moving. The sense of smell plays an important role in the life of this species, helping in the search for mating partners and prey. Also, the sense of smell allows this species to distinguish the water of different currents during its wanderings in the ocean.
This is a semi-deepwater shark species that makes daily vertical migrations: during the day it stays at a depth of 450-750 m, and at night it emerges to the surface. The main part of the population keeps above deep waters, but some groups of sea onza hunt in the offshore parts of the ocean. The sea onza feeds on large cephalopods and vertebrates, attacking them from below and tearing the belly. For a well-protected prey like turtles, it first bites or damages its limbs, after which it finds the weak points of the shell, and crushes the prey with its jaws.
Mating takes place in the summer months and in early autumn. At this time, violent mating games begin on the surface of the water, lasting until morning: males chase females, driving competitors away. Sometimes they fight fiercely for the female, striking the opponent with ramming blows with their heads in the sides or stomach; the weakest individuals often die in such fights. The sea onza, like the cachalot shark, is viviparous. The rate of reproduction of this species is very low: pregnancy lasts 16-17 months, and 2-3 juveniles are born. The body length of newborn individuals is 2.5-2.7 m; their first food is egg films, which they eat immediately after birth. Young individuals often die in the teeth of large fishes (including their congeners) and sharkodiles. Sexual maturity comes at the age of 12-14 years; life expectancy is up to 70-80 years.

This fish species was discovered by Nick, the forum member.

Disk-headed shark (Platysqualus cephalodiscus)
Order: Dogfishes (Squaliformes)
Family: Flat-headed sharks (Platysqualidae)
Habitat: coastal waters of the tropical zone of Indian and Pacific oceans.

Picture by fanboyphilosopher

Significant changes took place between Holocene and Neocene among the sharks. Because of the “planktonic catastrophe” in the oceans, following the numerous fish of the open ocean, the pelagic sharks disappeared as well. Near the coasts, the mass extinction first of all affected all the animals that dwelled on the coral reefs. The inhabitants of coastal waters, including sharks, began to evolve actively after the stabilization of the conditions in the ocean, occupying places in the new ecosystems. Sharks, in spite of the changes in the natural conditions, did not yield their place of supreme predators, and among them appeared forms, that obtain their food by the most diverse methods.
One of the strange sharks of Neocene is the whimsical-looking disk-headed shark, species no more than one-and-a-half meters in length. This fish is to some degree an analog of the hammerhead shark from the human epoch, but its appearance is somewhat different. The head of the disk-headed shark is very wide, flattened vertically and rounded on top. This form of head is caused mainly by the outgrown maxillary bones. The gills are located on the upper side of head disk, at its rear edge. The head partly provides lift during the movement of the fish; therefore the thoracic fins of this form have grown in length and are comparatively narrow. There are two dorsal fins, both bearing on their front edge tough and poisonous spines, inherited from their ancestor – one of the species of squalid shark. The tail fin has a very long and pointed upper portion. This species of sharks lives near the sea-floor at the depths from 1 to 50 meters. The disk-headed shark does not avoid fresh water and frequently hunts in the mangroves, remaining in puddles during the ebbing tides. In river mouths this shark lives in places with strong undertow and water is brackish.
The body of this species is beige with numerous dark spots, small on the head and the fins, and large on the body. On the back of the shark the spots merge into an uneven strip that goes along the length of the backbone.
The eyes of the disk-headed shark are small, located on the front edge of the head disk. The snout characteristic for the sharks in this species is quite short and almost does not disrupt the disk-shaped form of the head – it only slightly protrudes forward between the eyes of the fish. The narrow vertical slit-shaped nostrils are located next to the internal edges of the eyes. The eyes of this shark shine in the darkness with greenish color – a layer of the cells, rich in guanine, underlines the retina. The sight of this species is good, but it plays only a secondary role in hunting of this species.
The specific form of the head of the disk-headed shark is caused by the presence of special adaptation for the search of prey. The lower side of the head and edges of the jaws of this shark are supplied with a large number of electro-receptors, which make it possible to track down the minimum electrical activity at the small distance from the skin of the fish. When hunting, the disk-headed shark swims above the sea bottom, holding the lower part of its head parallel to the flat sea-floor. In this case, the electro-receptors indicate the presence of the animals that are burying into the sand, which this fish eats – cephalopods, crustaceans and small fishes. The mouth of this fish is relatively small, but because of the mobile joints between the maxillary bones, it can be extended downwards in the form of a tube. The teeth are numerous, thin, designed for splitting – they are designed to catch middle-sized, but slippery prey. Swimming above the sea-floor, the fish literally “scans” sand in search of hidden animals. After determining the location of prey, it with one strike puts the prey under its head disk. After sensing the attack, the prey, most frequently, attempts to bury itself even deeper, but the shark extends its jaws downwards, overtaking the prey. With this method of hunting, the shark gets plenty of sand in its mouth, but this is not a problem for the predator: the sand is forcefully ejected through the gills, while the jaws reach for the prey.
The disk-headed shark is viviparous. Once per year a female gives birth to twenty young sharks, completely ready for independent life. The young sharks mostly feed on free-swimming prey and their heads are less disk-like. At the age of approximately one year heads of the young sharks begin to widen. At the age of five years the shark reaches length of approximately 120 cm and can breed.

Translated by Bhut, the forum member.

Arrow-headed shark (Sagittoselache diplocauloides)
Order: Dogfishes (Squaliformes)
Family: Flat-headed sharks (Platysqualidae)
Habitat: coastal waters from the tropical to the warm-moderate zone of Pacific Ocean: Indonesia, the coast of Asia to the north of Japan Islands.
In Neocene, the sharks proved again the success of their evolutionary branch. Many species of these fishes disappeared after “planktonic catastrophe”, but those who survived, rapidly evolved, occupying the freed ecological niches. During evolution many species succeeded to survive, and many bizarre types appeared among them. Several species of sharks with very wide heads became the original analogues of the hammerhead sharks of the Holocene epoch.
A large representative of flat-headed shark family is the arrow-headed shark, a predatory fish up to 3 meters in length. This species of fish possesses a very characteristic appearance, and it cannot be confused with other fishes. The head of this fish has a form of a stylized arrow tip – it is flattened, extended at the edges, triangular in shape, with large lateral lobes turned backwards and to the sides. The lobes form the kind of wings and by function they supplement the pectoral fins. The eyes are located on the front edge of the lobes, approximately between the snout and the tips of lobes. They are large, and the pupils are capable to enlarge strongly: this is an adaptation for living in habitats with low illumination. The nostrils, positioned widely to the sides, are located next to the eyes.
The pectoral fins of this species are shortened and extended. When swimming quickly, this shark thrusts its pectoral fins against its body and their function is taken over by the head of the fish. In search of the prey, the arrow-headed shark slowly swims above the sea-floor. At this time, its head fulfills another important function – the receptors on its bottom side help to determine the presence of prey. Pectoral fins have also another very important function. The tips of pectoral fins of this shark are armed with a kind of claws – the part of the edge of fins is covered with several rows of increased skin “teeth”. They are larger in males – with their aid, the male retain the female during mating. Furthermore, these “claws” help the shark to escape from the storm. The arrow-headed shark dwells along shallow coasts, and it lies down into deep holes on the sea-floor and attaches itself before the beginning of storm, butting its fins against the walls.
The skin of the arrow-headed shark is dark grey in color, with dark strip located on the front edge of the head lobes. Another dark strip outlines the rear edge of the tail fin. The belly and the lower part of the head are brighter than background coloration. The upper fluke of the tail is approximately twice as long as the lower. The back fin is tall with a dark tip. At the front edge of the fins there is a small spine, which lacks a poisonous gland.
This shark lives only in water of oceanic salinity, and avoids fresh water, not entering the mouths of rivers. Because of this special feature, it does not compete with its close relative, the disk-headed shark. Also it feeds at a greater depth: from 3 to 100 meters and even deeper. This species is a bottom-dwelling shark, which feeds mostly on octopi and crustaceans. In contrast to its smaller relative, it does not dig in sand and patrols over rocky areas of the sea-floor. When hunting, the arrow-headed shark slowly swims above a reef. It senses the electrical activity of the nervous systems of the hidden animals. With sharp thrusts the shark flushes them out and catches them in its jaws.
The arrow-headed shark is viviparous. Once per year, the female gives birth to two large young up to 60 cm in length, already prepared for independent life. Soon after the birth, the female is again ready to bear young. The male of this species is smaller and slimmer than the female, with larger back fin. It finds the female by smell and begins to pursue it. If there are several males, they swim after the female as one. Usually, in several hours, the female chooses one male that chases away the rest ones. The mating occurs in a stomach to stomach position. The male grabs the female by the pectoral fins during the entire mating. During it, the fishes swim slowly in the deep, open water; the female usually swims with its back upwards and the leading role in this undertaking belongs to it. After the mating, the male leaves the female.
The young arrow-headed sharks differ from the adults by their darker colours with brighter spots in upper part of the body. They have narrower heads with the smaller lateral lobes, which do not prevent its birth. As they grow, the lobes of the head grow, and it takes the form that characteristic for this species. At the age of five years, the young shark becomes capable of mating. The lifespan of this species reaches 30 years and more.

Translated by Bhut, the forum member.

Zeus's shark (Electroselache zeusii)
Order: Dog sharks (Squaliformes)
Family: Electric sharks (Electroselachidae)
Habitat: Atlantic, depths from 50 up to 300 meters in tropical and subtropical area; at night emerges to water surface.

Picture by Lyagushka

During the evolution process organs and tissues may considerably change the functions in comparison with their initial applicability. So, at fishes belonging to various systematic groups muscles had changed to electric organs becoming the effective adaptation for orientation and hunting weapon. In Neocene new groups of fishes had got electric organs. Zeus's shark living in Atlantic Ocean is an electric species of sharks. It is an example of parallelism with rays of order Torpediniformes, known even in human epoch as owners of strong electric weapon – hunting and protective adaptation. Zeus's shark has received the name by analogy to skill of antique god Zeus to fulminate, but, as against the mythical person, it makes it in real life.
This species is a pelagic fish of about 2 meters long weighting up to 150 kgs and living in top layers of water in temperate and subtropical zone of Northern hemisphere. Appearance of Zeus's shark is typical for the majority of sharks – it has streamlined body, pointed fins, unequally-lobed tail with the increased top lobe. Pectoral fins of this shark are rather short: it is able to swim quickly only at short distances. Colouring of body of a Zeus's shark is light blue with black spots on tips of pectoral fins. The top lobe of tail from the tip up to middle is colored white.
The anatomy of head of this shark is remarkable. It has wide short snout, and skull is expanded in top part, forming two big crests directed sideways and a little bit upwards. These crests serve as original stabilizers of position of body at swimming. Eyes are shifted downwards under stabilizer crests. The distant relative of this species, huge cachalot shark (Physelache planicephala), has a similar structure of head. Mouth of Zeus's shark is small; jaws are attached to skull and to each other by elastic ligaments. Teeth of this species of sharks are peaked, needle-like, small and weak; they grow on jaws forming six – eight lines. It is impossible to cut half-and-half even the soft body of squid by them; they serve only for keeping of prey. Jaw muscles of this shark are also very weak. It is connected to the fact that the significant part of strong muscle closing the mouth at ancestors had turned to electric organ and had lost the ability of contracting. Besides crests on skull of this fish were also formed for increase of size of electric organs which are attached to their basis. The voltage creating by Zeus's shark may reach 250 volt at force of current up to 2 amperes.
Zeus's shark hunts schooling fishes, pelagic crustaceans and cephalopods. Usually it slowly swims in thickness of water, but, having felt approach of school of prey, makes a throw. Wedging in school of sea animals, shark produces some strong electric pulses one by one. It happens enough to kill or to paralyze several fishes or squids. Usually the most part of school escapes, but this shark always gets some prey animals. It simply swims across the “battlefield” and gathers shocked fishes. This shark swallows prey entirely: jaws can opened widely due to extensible and elastic ligaments. Due to the ability to produce strong electric impulses the present species of sharks does not have any satellite animals of various kinds usually accompanying sharks.
Zeus's shark is a solitary species; only during the pairing some males may court for one female. During the courtship ritual males produce the short weak electric impulses having signal function. Female also replies them with electric impulses. If it is not ready to pairing, it banishes male by stronger electric pulse.
This species is viviparous: after the pregnancy lasting about 7 months the female gives rise to up to 6 large (about 30 cm long) and independent young sharks. Young ones the first days of life can not produce electric impulses – it protects the female at delivery process, but makes young sharks very vulnerable. During the first days of life the electric organ starts to develop, and at young fishes grown up a little electric impulses are already strong enough to frighten off the predators really dangerous to fishes of their size. Sexual maturity at young Zeus's sharks comes at the age of 4 years, and life expectancy reaches 25 years.
In northern part of Pacific Ocean Zeus's shark is substituted by close species – Taranis’s shark (Electroselache taranisii), named after Taranis, the god of lightning of ancient gauls. This species differs from Zeus's shark in larger size – up to 3 meters at weight more than 200 kg. Because in the top layers of water in Pacific Ocean sharkodile (Carcharosuchus deinodontus), ecologically replacing large sharks and being an active predator dominates, in day time this shark keeps at the depths of about 100 – 200 meters. Possible, the settling of an ancestor of these fishes had proceeded through Panama Passage. Taranis’s shark also has electric weapon. Fertility of females of this species reaches to 10-15 young fishes.

Assarhaddon (Asarhaddon bathypelagicus)
Order: Dog sharks (Squaliformes)
Family: Electric sharks (Electroselachidae)
Habitat: Pacific Ocean, depths from 250 to 400 meters.

Picture by Lyagushka

In Neocene, sharks have taken their place among the electric fishes. In the human epoch, they only possessed virtuoso abilities to sense electric fields, but in Neocene, forms capable of generating an electric field with the necessary properties appeared among them. One of these species is the Zeus’s shark (Electroselache zeusii), which stuns its prey with strong electrical discharges. But this is not the only species that uses electricity while hunting. In the Pacific Ocean, the Taranis’s shark lives in surface waters, and at depth it is replaced by another species – assarhaddon.
Assarhaddon is about a third larger than the Zeus’s shark: the length of an adult is about 270 cm; three-meter individuals are less common. It has a more slender body, similar to a torpedo, and less expressed head crests. Vision is less developed than that of most fish in this zone: the eyes are very small. The weakness of vision is compensated by a network of sensitive cells formed by a lateral line. Due to it, the fish perceives waves spreading in the water when other animals move. Also, these cells are able to detect even very weak electrical activity.
The body color is dark gray with lighter fins and tail. Assarhaddon’s mouth is almost at the same level with its eyes – this feature allows it to gather prey more efficiently. The fins in the front part of its body are adapted mainly to turn around quickly – the deep dorsal and caudal fins serve as stabilizers. The shark’s body is very flexible, so it can turn around on the spot very quickly.
The closest relatives of assarhaddon, electric Zeus’s sharks, use electricity generated as “targeted” discharges during hunting. These sharks also attack their prey with “weapons of mass destruction”.
Assarhaddon’s skin is covered with a special substance that conducts electrical current well. Having appeared in the shoal of fish, the shark passes several strong impulses from its head to the tail; the electric wave spreading in all directions stuns quite a large number of prey items. At the same time, this technique cleanses the shark from most ectoparasites.
Assarhaddon swim poorly, preferring to wait for the fish to stumble upon it. Assarhaddon also tricks the senses of its prey with electricity. Floating in the water column, the shark emits weak pulses of a special frequency, “off-tuning” the “navigation devices” of other fish and directing them right to the predator. When a schoool of prey surrounds assarhaddon from all sides, it activates its hunting weapon and begins food gathering. Due to this hunting method, assarhaddon can feed on small prey, avoiding competition with other large semi-deepwater fishes.
It is a viviparous species. After a pregnancy lasting up to 15 months, the female delivers two very large juveniles – each up to 70 cm long. They are able to generate an electric field and feed themselves immediately. The survival rate of offspring is quite high due to the large size of newborn individuals. Sexual maturity comes at the age of about 5 years; life expectancy is up to 40 years.

This fish species was discovered by Mex, the forum member.

Tripod shark (Abyssotripodus cheirognathus)
Order: Ground sharks (Carcharhiniformes)
Family: Tripod sharks (Abyssotripodidae)
Habitat: Atlantic Ocean, abyssal sea bottom areas.
At the turn of Holocene and Neocene, a global ecological crisis occurred in the ocean, called the “plankton catastrophe” – the mass extinction of phyto- and zooplankton. This crisis led to the extinction of a significant number of pelagic nectonic organisms, and its consequence was also the extinction of deep-sea animals, almost entirely dependent on the supply of organic substances from the upper water layers. In the Neocene, the depths of the ocean were repopulated, and some of their inhabitants are remarkable in their very bizarre appearance. The tripod shark, which lives on the ocean floor, belongs to such species.
This species is a typical deep-sea inhabitant with all the characteristic features. The tripod shark is a relatively small fish: the length of an adult does not exceed 40-45 cm. This fish has a very soft skeleton consisting of slightly calcified cartilage. The hardest parts of its body are jaws and teeth. The body has an elongated streamlined shape with a blunted snout. The coloration is pale, pinkish-gray with large blood vessels seen through the skin. The skin on the underside of the body is thin and stretchable. It is almost transparent; the heart beatings and intestinal contractions are seen through it, as well as prey that has been swallowed, but not digested yet.
The head of this fish is shortened; the bases of the pectoral fins are shifted forward and are actually above the gills. The branchial clefts are shifted downwards and appose on the underside of the pharynx.
It is a benthic fish that “walks” on the bottom using long pectoral fins and a strongly elongated anal fin (this is an example of convergence with the deep-sea teleost fish Bathypterus known in the human era). The front edges of the pectoral and anal fins are elongated and transformed into elastic cartilaginous “rods” on which the fish rests when not moving. The caudal fin is deep; its lower lobe is only slightly smaller than the upper one. When the fish “stands” on its fins, the tail does not touch the bottom. Tripod shark swims poorly and reluctantly, preferring just to stand motionless on the bottom on its “tripod”. The disturbed fish makes a rush and accelerates with the help of movements of the caudal fin. The tripod shark swims long distances, flapping its elongated pectoral fins like wings.
Among the senses, the most developed are senses of smell, touch and electrical sense. This fish is blind: the eyes have completely disappeared, and only in young individuals dark spots are visible under the skin in place of the eyes; in adult fish, further reduction of the eyes and their replacement with connective tissue takes place. The sense of smell of the tripod shark is very acute. The nostrils are large and slit-shaped, located at the edges of the head. The ciliary epithelium provides a constant flow of water through the nostrils. The lateral line channels form a dense network on the head. There are numerous electroreceptors around the mouth and on the underside of the body.
This fish species is a benthophagus and feeds on worms, small crustaceans and echinoderms (holothurias), as well as fish. The anatomy of the shark’s mouth is remarkable: it is retractable. The jaws are attached to the skull on stretchable ligaments. The fish stands above the bottom on a tripod of fins and lowers its jaws on movable ligaments downwards, scooping burrowing invertebrates out of the ground. The teeth of this shark are numerous, long and thin. Capturing a portion of the sediment with prey, the fish releases silt through the branchial clefts. Having detected the presence of small fish, the tripod shark overtakes it with a quick rush.
The reproduction rate of this species is slow. It is a viviparous species; the female gives birth to one large juvenile once a year. The length of a young shark is half the length of the mother. It is fully developed and immediately begins to lead the same lifestyle as adults. Males of this species are less common than females. The tripod shark is characterized by parthenogenesis, and after the only fertilization act, the female can bring up to five juveniles developing in her ovary from resting zygotes.
It becomes sexually mature at the age of 4 years, and its life expectancy reaches 30-35 years.

Meganesian sawfish (Pristis meganesianus)
Order: Sawfishes (Pristiformes)
Family: Sawfishes (Pristidae)
Habitat: rivers of Meganesia.

Picture by Lyagushka

During Holocene sea ecosystems had suffered not less than land ones, because people polluted ocean and caught many species of food fishes and invertebrates, not reflecting about the future. Besides “planktonic accident” had caused destruction of great number of species of pelagic animals. Species had not died out during the reorganization of ecosystems, should adapt to existing is sharply changed conditions of Neocene. Bentic communities of coastal waters had suffered lesser; more kinds inhabited such areas had kept. Dwarf sawfish (Pristis clavata) was among ones managed to survive in epoch of anthropogenous pressure and biological crisis. Having managed to go through threat from the side of people in Holocene, in Neocene it was compelled to adapt to new neighbours: Neocene saw-nosed crocodile (Pristisuchus serratorostris) had occupied the ecological niche of sawfishees in brackish reservoirs of Meganesia, and other crocodile species, giant sharkodile (Carcharosuchus deinodontus), has risen on top of food pyramid in tropical waters of Pacific Ocean. In such conditions the way of life of sawfish could not remain former. It had adapted to new neighbours and conditions of life by the same way, as well as some other species of cartilaginous fishes. Like pike shark (Esocisqualus rivularis) of Asian rivers and river shark (Neocarcharinus flumineus) of East Africa, dwarf sawfish had passed to life in fresh water. This species lives in Meganesia where there is enough forage and there are no large competitors. Meganesian sawfish inhabits rivers flowing to Eyre Gulf. In Arafura Lake This fish species is superseded by saw-nosed crocodile, and submitted by only separate individuals.
Meganesian sawfish is not so large kind of rays: its maximal length is 60 – 80 cm. The largest individuals, sometimes up to one meter long, live in coastal freshened zone and mangrove thickets of Eyre Gulf. Colouring of flattened body is concealing: greenish-brown (at females there is a prevalence of yellow shade). The snout has kept the characteristic sawtooth shape, but became much shorter, than at ancestor – less than one third of total length of fish. On it 9 – 11 pairs of teeth grow; they are sharp enough and quite capable to deliver dangerous laceration to predator or prey. But by its habits Meganesian sawfish is sluggish and inactive fish, preferring to attack from an ambush instead of prey chasing. This ray eats small river fishes and invertebrates, dexterously digging them from silt by snout. The mouth of this fish is located on the bottom side of body, and fish swallows prey, preliminary having pressed it to the bottom by body. At threat of predator attack this fish gets deeper into thickets of aquatic plants, or is simply dug in silt. However the seized fish strikes wounds to the enemy by snout. Male has longer snout, than female; also it is more graceful and smaller a little, than female.
Meganesian sawfish has very small eyes shifted to the basis of snout. Bad sight is quite compensated by a circuit of electroreceptors on skin, especially on bottom part of body. With their help fish easily finds out the prey hidden in sand, in total darkness. This adaptation allows Meganesian sawfish to hunt successfully even during high water, when rivers carry a plenty of dregs.
This is live-bearing species of fishes similarly to its ancestor. The female bears posterity within approximately eight months and gives rise up to four young fishes completely ready to independent life. At newborn sawfishes snout is protected with dense cover of jelly-like mass, which falls down right after birth. To one-year-old age approximately half of young growth stays alive, but further death rate reduces. Female becomes sexually mature at the seventh year of life. Total life expectancy of Meganesian sawfish reaches 40 – 50 years.

This fish species was discovered by Bhut, the forum member.

Oshadagea (Oshadagea aquilla)
Order: Stingrays (Myliobatiformes)
Family: Whiptail stingrays (Dasyatidae)
Habitat: North America, Miche-Nama Lake.

Picture by Alexey Tatarinov

During the interglacial epochs, the territory occupied by Hudson Bay in the human era was flooded by the sea several times. Glaciers filled a huge basin in the north of the continent, but after their retreat, the sea returned again. Gradually, the connection of Hudson Bay with the ocean became weaker and weaker, as each glaciation deposited a layer of moraines at the mouth of the bay. At the end of the Ice Age, the mouth of Hudson Bay appeared completely closed. A large number of marine animals of various groups had been trapped there. When the salinity lowered and the bay turned into Mishe-Nama Lake, some of them died out, but some species managed to adapt to life in fresh water. Mish-Nama Lake harbors many species that are relics of the former condition of this water body, the descendants of marine animals.
One of the largest fish species living in Mishe-Nama Lake is oshadagea, a giant stingray. The appearance of this species has remained quite recognizable: this is a stingray with a fin span of up to 2 meters and a long thin tail equipped with a spike. The name of this species comes from the name of the mythical eagle capable of carrying the whole sea in a depression on its back – this fish swims in a characteristic way, flapping its pectoral fins like wings. The body outline of this fish is diamond-shaped; the width exceeds the length (without its tail). The upper side of its body is olive-brown; the underside of the body is white. The edges of the pectoral fins are darker than the general body color. A long (up to 30 cm) jagged poisonous spike grows on the tail, and several smaller spikes are located next to it.
This species is an active predator. It eats mainly benthic fish and crayfishes, covering them with its body and swallowing. Sometimes this stingray catches prey swimming on the water surface – small waterfowl or mammals appeared in the water. To do this, the fish emerges to the water surface with its belly up and sucks the prey in from below.
Usually oshadagea keeps in the lake itself, in coastal shallows area. Young fishes often enter rivers where the competition with adults for food is not so strict. Often, fishes arrange “beds” for themselves – places with soft ground, where underwater vegetation is torn out by their movements. In such places, the ray usually rests and hides, burying itself in the ground. In summer, when the water is warmed up rather good, oshadageas are found along all the shores of the lake and in many rivers flowing into it. During the spring-summer activity, these rays are quite aggressive and territorial; only during mating, the female allow males to enter her territory. In a seasonal climate, these rays have a kind of hibernation: the oshadagea winters at the bottom of deep pools, gathering in groups of several dozen individuals. At this time, the ray is inactive; it burrows into the silt or just lies on the bottom. Individuals of different sexes and sizes are tolerant of each other during the winter, and young stingrays often lie atop of adults.
In early spring, after wintering, these rays begin the mating season. Males begin to chase females actively (sometimes 2-3 individuals at once do it) and try to hold them by keeping the tip of the female’s pectoral fin in the mouth. Mating takes place in the water column. Oshadagea is a viviparous species; fecundity is up to 3-4 juveniles. Pregnancy lasts almost a year, and young rays are born at the end of winter, shortly before the mating season. The body width of a newborn ray is about half a meter; it is born with folded fins and unfolds them immediately after birth. The coloration of young individuals is mottled: large spots of a darker shade are scattered on an olive background. The survival rate of the offspring is high, since the juveniles are large and can immediately feed on insect nymphs, small crayfishes and benthic fish. In addition, due to the rather large size of young individuals, cannibalism does not take place in this species. Sexual maturity occurs at the age of about 3 years, and life expectancy reaches 50 years or more.

Butterfly stingray (Papiliotrigon pumilis)
Order: Stingrays (Myliobatiformes)
Family: Whiptail stingrays (Dasyatidae)
Habitat: Eyre Gulf, shallow water areas, mangroves.

Picture by Ilya

The presence of the Eyre Gulf in the geography of Neocene Meganesia is one of the key points that have a tremendous influence on the ecology of the continent. This body of water is a source of water that falls as a rain in the central regions of the continent, which makes large areas more habitable. Eyre Gulf is shallow; water enters it from the ocean through the mouth and from rivers flowing down from the mountains in the eastern part of the continent. Because of this, the salinity of the water varies widely – from almost oceanic near the mouth to slightly brackish water in the northern and eastern parts of the bay. The shallow waters of the bay are very warm, and therefore the oxygen content in it can drop significantly. In such conditions, it is hard to survive for the most fish species, so the ichthyofauna of the gulf is poorer than at the ocean coast or in the rivers flowing into the gulf.
Among the inhabitants of the Eyre Gulf, there is a butterfly stingray, a miniature representative of stingrays adapted to life in coastal shallow waters. The width of the diamond-shaped body of this stingray is only 18-20 cm; the length of the tail is about 15 cm. The coloration of the upper side of the body may vary for camouflage purposes, but usually it is sandy yellow with large black spots in the middle of the body, that greatly decrease towards the edges of the fins. In some individuals, the posterior edges of the pectoral fins are bordered by a narrow black stripe. This color can lighten to grayish-white with bluish-gray spots. In a stress condition, this stingray can turn almost completely black. The underside of the body is porcelain-white.
The eyes and spiracles of this fish are slightly raised compared to their position in other rays. It takes place due to some peculiarities of its behavior: when the oxygen content in the water is little, this stingray emerges to the water surface and sucks air in through the spiracles, throwing it out then along with the water through the branchial clefts. In this way, the fish provides itself with oxygen. At this moment, the fish swims under the very surface of the water, “fluttering” with its pectoral fins, like a butterfly with its wings.
Otherwise, the lifestyle of this stingray does not differ from that of other rays. The butterfly stingray feeds on crustaceans and small benthic fish, covering the prey with its body. In case of danger, the ray hides in the sand or among the bottom debris, throwing it over itself with the movements of its fins. On the tail of this fish there is a strong jagged spike, also serving for self-protection. On the back side of the spike, a groove filled with a poison of jelly-like consistency stretches.
The mating season is not sexpressed; males search for females ready to reproduce by smell. This fish is viviparous; after a pregnancy lasting 4 months, the female gives birth to one large juvenile (its body width is about 10 cm). At this time, there are several more “preserved” embryos in her ovaries. After the delivery, the development of the next-oldest embryo begins. Young rays hide in thickets where adults cannot penetrate, and often gather in small groups in the roots of Pandanus and other mangroves. Their coloration is more saturated than that of adult fish, and a black stripe borders the entire disc of the body. They quickly grow a poisonous thorn.
Sexual maturity in this species comes at the age of 3 years, and life expectancy reaches 20 years.

Estuarine Oval Ray (Megalolophus carcinophilus)
Order: Stingrays (Myliobatiformes)
Family: Stingarees/Round Stingrays (Urolophidae)
Habitat: Lagoon bottoms and estuaries in the river-mouth of Eyre Gulf, Meganesia.

Picture by Lyagushka

In the Holocene, stingrays and sharks suffered to some extent for hunting, for their fins as an ethnic delicacy in Asia. And thus, some larger species of ray suffered by the end of the Holocene. Coming to replace them in the Neocene were descendants of round stingray or stingaree, Urolophus, which radiated into larger sizes and more varied niches.
This species is a relatively large one, reaching up to a meter in diameter. In shape it resembles a bigger version of its ancestor, outline of the body is like an oval, eyes and spiracles are perched high on the body in an almost periscope fashion. The tail is short, but bearing a large barb which is serrated and secretes potent venom. Pattern is a pale brown with darker brown mottling and spots, appreciable particularly around the eyes, underside is dirty white.
The diet of this animal is a little more varied than its ancestor, while it feeds on crustaceans of all sorts, worms and bivalves, it will also hunt bony fish actively, though it will prefer slow moving ones like sleeper gobies and catfish. When inactive, it buries itself in sand or mud, with only the eyes and spiracles visible. It is generally most active at night and during twilight.
Breeding occurs during the dry season, where males will inseminate the female with their large claspers. Females retain the eggs internally, which hatch inside, first sustained by the yolk, and then by “milk” from the uterine walls. Small litters (about 6 or 7) of well developed young are born live, at about 20 centimetres long. Lifespan is up to 19 years, sexual maturity is reached at about 40 centimetres in size.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Blind African electric ray (Caeconarke tectus)
Order: Electric rays (Torpediniformes)
Family: Torpedo electric rays (Torpedinidae)
Habitat: the mouth and lower reaches of the Zaire, rivers along the Atlantic coast of Africa.

Picture by Alexey Tatarinov

Changes in marine ecosystems at the turn of Holocene and Neocene caused the extinction of many species of living organisms. To a greater extent, this affected planktonic and nectonic species of the open ocean, and to a lesser extent – benthic and coastal species. Some species of benthic organisms in the process of evolution began to develop new habitats, and some of their species settled in rivers via brackish waters of estuaries and mangroves. This process was especially active in the tropics, where new species from groups that had not previously been found in fresh water appeared. One of these species is the blind African electric ray, a freshwater electric ray that descends from the Atlantic Torpedo torpedo ray, a common species in the human era.
Blind African electric ray is a fish that lives at the river bottom. The low transparency of river water carrying a large amount of suspension led to a reduction in vision in this species. The blind African electric ray orients itself and searches for prey with the help of an electric field generated by large electrical organs lying on the sides of its body. It is a fish about half a meter long, with rounded fins and a rather thick disc-shaped body. Its coloration is not bright: gray with speckles on the body and in the middle part of the disc. The underside of the body is white or yellowish.
The eyes of this fish are completely reduced; only in young individuals dark spots are visible under the skin in place of rudimentary eyeballs. The lack of vision is compensated by a well-developed sense of smell and electrical sense. The electrical organs inherited from the ancestral species are well developed and capable of generating electric fields and strong single discharges.
This species is a predator and catches bottom-dwelling fishes and crustaceans, including those burrowing into the sand. During the hunt, the ray swims some centimeters above the bottom, monitoring the changes of its electric field. Sensing the presence of a small animal by changes in the electric field, the ray produces a strong discharge that kills the prey, then covers it with its body, digs up sand and swallows it. Having felt the presence of a large animal, the fish quickly buries itself in the sand, defending itself with an electric discharge if necessary.
Blind African electric ray breed at any time of the year. The male searches for a female ready to mate and chases her for several hours, after which mating takes place. This is an ovoviviparous species: from 4 to 9 eggs (depending on the size and age of the female) are incubated in the mother’s body for 6 weeks, and the young fish breaks through the egg shell at the time of delivery. The newborn juvenile reaches a length of 7-8 cm. It is able to generate a weak electric field immediately and can perceive light passing through thin skin. Young blind African electric rays migrate upstream and live in shallow rivers for the first two years of their life. They are nocturnal and migrate to the main riverbed as they grow. They become sexually mature at the age of 4 years, and life expectancy of this fish reaches 30 years or more.

Bunyip (Teratoceratodus bunyip)
Order: Australian lungfishes (Ceratodiformes)
Family: Barramundas (Ceratodidae)
Habitat: rivers of Eastern Australia to the north up to Carpentaria Lake.

Picture by Alexey Tatarinov
Colorization by Carlos Pizcueta

The bunyip is a mythical predatory aquatic monster from Australian rivers. In Neocene the legend about this creature had been unexpectedly embodied in reality. Crocodiles had died out in an ice age, but to change them in their ecological niche the new predator had come, quite suitable by its habits to the image of legendary monster.
Ancestor of this creature is not a reptile, but fish, the amazing Australian barramunda (Neoceratodus forsteri). As it is paradoxical, this creature had got advantage in survival because of human activity: in XX century of human epoch this fish had been widely settled by people at the continent for the purpose of preservation of this species. It was successful act, and the small population of barramunda had survived in lakes at bottom of Great Dividing Ridge. To survive, these fishes had starting to master other food sources, than were at their ancestors. Rather large animals, mainly vertebrates, are including to ration of Neocenic bunyip. This fish had replaced the extinct crocodiles at top of food pyramid.
It is strictly freshwater fish. Bunyip does not come to Carpentaria Lake far from coast because of residual salinity of depths (this lake represents a former sea gulf), moving only along coast and is settling in swamps surrounding this lake. Bunyip does not live in Arafura Lake at all: it is even more salt, and here one of relic species of crocodiles replaces it. But bunyips live in the rivers running into these lakes, and in circuit of channels and bogs of tropical rainforest.
Bunyip not so strongly differs from the ancestor: it had kept features of structure characteristic for the barramunda – flipper-like fins, large scale and one lung. But it had appreciably increased its size: it is a huge predatory fish up to 4 meters long and weighting over 400 kg. The female is larger and paler than male, but at the male head is larger. The tail of bunyip is short, rounded and expanded in comparison with the lengthened peaked tail of barramunda. It is used only for sharp throws for catch, and not hunting fish swims with the help of movements of wide flipper-like paired fins.
The head of bunyip had turned to true ram: the cartilaginous skull is considerably strengthened by shell scutes. Corneous plates, with which help fish grasps and dismembers catch, have peaked cutting outgrowths. They can split half-and-half seized catch: fish, lizard, bird or mammal. Bunyip avoids only attacks on the adult turtles protected by firm carapace, but this fish swallows the young growth of turtles entirely and exterminates it in plenty.
At the bunyip there are small eyes and bad sense of sight, but sharp sense of smell and sensitive lateral line. Even in darkness this fish can easily find and seize small frog swimming several meters far from predator.
Bunyip is bad swimmer, but it is the master of camouflage: its colouring – brown with dark speckles – makes it badly seen among river dust: driftwood, trunks of trees and layer of fallen leaves. Having masked, the fish passively expects catch, attacking it by fast throw. About two - three times at hour bunyip emerges for air, though in case of necessity and in fresh water, rich in oxygen, it can make it only once per hour, and even less often. At breath the fish utters loud groaning sound especially far heard in silent night. Each fish protects territory from neighbours, and this sound distributing under water, warns neighbours of territorial claims of bunyip.
The bunyip tolerantly concerns to life in pond with muddy stinky slush to which water turns during a drought: it respires by air, and the zero contents of oxygen in such water is indifferent to it. However this fish does not live in completely drying up reservoirs, because it has no special mechanisms promoting preservation of water in body. When the drought begins, bunyips leave inundated reservoirs and migrate to the central channel of river, or stay in deepest ponds. When in river channel many fishes of this species swim together at once, between them there are fights and many borders of territories are reconsidered. Though in inundated reservoirs there are young and weaker fishes, and in the main channel the strongest individuals live, some young applicants had “grown up” till the rain season, more often succeed to win at older individuals a place to themselves. Fight is accompanied by demonstration of forces, pushes by sides and impacts by head. When forces are equal and any contender does not concede, jaws are used for fight. Some old individuals have characteristic traces of stings on back and sides – four deep V-shaped small holes placed in corners of rectangular, staying from the pointed ends of cutting plates.
The spawning of bunyips occurs once a year in rain season: at this time many fishes leave the basic channel, and the competition is reduced. The unitary fast spawning is a consequence of very short period favorable for spawning at ancestors of bunyip during the ice age (at the barramunda spawning is portional and dragged out to some months). For spawning the male chooses underwater small-leaved plants, clears them of silt by movements of fins, carries off stones and dust, and starts to invite the female to the prepared breeding bottom. It pushes the female by head, swims around of chosen bush of water plants, emerges and specially “sings”, exhaling air with all its might.
In clutch of bunyips there is up to thousand of very large grains of roe (their diameter is about 2 cm). Fishes spawn eggs in plants prepared by male, and he stays to protect territory around of clutch, not caring special way about eggs.
Egg incubation lasts about 2 weeks, and then approximately equal time the larva passively lives at the bottom, hiding from enemies, not eating and digesting the rests of contents of yolk sac. Later it passes to feeding by small water invertebrates and fry of fishes. At one-year-old age the bunyip reaches length about 10 cm. Further, having transited to feeding by fish, fish strongly accelerates the growth rate, and at ten years' age, at length about two meters, the fish already can take part in spawning. The maximal life expectancy of bunyips may exceed 150 years.

River boltergiller (Potamocetus balaenognathus)
Order: Osteoglossoids (Osteoglossiformes)
Family: Aravanas (Osteoglossidae)
Habitat: rivers of South America, central part of channel.

Picture by Amplion

After the ice age had marked border of Holocene and Neocene, climate began considerably more humid: seas have filled coastal sites of land, and areas of water evaporation had increased. Rains had returned again to equatorial areas of Earth, having filled with water great rivers. Amazon and Hyppolite, flowing in parallel to it, are two rivers gathering water from significant part of South-American continent. Each of these rivers differs in large width, overflowing at tens kilometers and flooding riverbank woods.
Waters of these rivers gather organic substances from huge woody area, and current of the rivers is slow enough. Due to it in central part of river channel in upper layer of water plankton (algae, small crustaceans and worms) plentifully develops. Shoals of fishes serving as food to some predatory reptiles, mastered channels of big rivers, eat river plankton. But these predators respectfully make way for one of inhabitants of channel – huge four-meter fish slowly swimming near the surface. This fish inspires respect in size, but it is not furious predator. It is the river boltergiller, the descendant of aravana (Osteoglossum). This fish does not represent danger for animals longer than 3 – 4 centimeters: it eats plankton, tiny schooling fishes and fry.
Due to abundance of food this river giant easily increases weight up to about 300 kgs. Body of the boltergiller is compressed from sides, especially in tail part, right after abdominal fins. Back, head and top part of tail make practically straight line: it is an attribute of top-skimmer fish spending the most part of time at water surface. Boltergiller swims rather slowly, bending by all body like eel. The tail fin at it is small and narrow, grown together with anal. Wide band-like anal fin stretching from middle of body up to the end, is the main organ of movement of fish. The back fin is reduced up to the several fin rays not connected by membrane.
The head of boltergiller is high, and mouth can open widely. Thus jaws draw downwards and in sides, forming wide funnel. Gills of fish had changed to effective filter device: branchial stamens have turned to similarity of dense grid, detaining even smallest zooplankton. Eyes of boltergiller are rather large, orange-colored. In spawning season eyes of males get ruby-red color. On chin pair of characteristic wattles directed forward stick.
The body of fish is covered with large rounded scale. Colouring of body is silvery with blue shine and grey back. The anal fin is bordered by black strip.
The boltergiller spends all adult life far from river coast. It is solitary fish, only at “pastures” rich in river plankton it is possible to meet at once several fishes. They do not pay attention against each other.
The spawning season at these fishes lasts within all year, but fishes show especial activity after rain season when water in the rivers is rich in plankton. Male ready to spawning declares itself by high jumps from water. At times fish takes off from water vertically at three - four meters upwards, and plops down on side, splashing a cloud of splashes. The booming sound lets females know, that the male is ready to take part in courtship. This fish is monodin. Spawning proceeds in thickness of water. Female spawns large egg in portions, male fertilizes them, and then female picks them up by mouth. Such acts repeat, while all eggs will be spawned.
At this species not only the female, but also the male, shows care of posterity: when all eggs are spawned, female delivers a part of clutch to the male from mouth in mouth. Term of egg incubating is about one week. All this time fish, bearing posterity, does not eat. But it does not harm to its organism: fishes are able to fast for very long time. Fry spend first days in mouth of the parent, but starting to swim, they leave it and further live independently. When the fish bearing posterity, feels, that fry are ready to leave the refuge, it approaches to riverbank and comes into small rivers. Here parent opens mouth, and fry swim out in searches of food.
Larvae of river boltergillers feed in coastal waters, occasionally remaining in lakes after river floods. Here, far from the majority of predators, fishes grow fat, and at the following floods leave temporary refuge and swim to the basic channel of river. They become sexual matured at the fifth year of life at length about two meters.
The boltergiller differs in significant longevity: this fish can live up to 60 - 70 years.
In shallow rivers of Amazon and Hyppolite basins there are close species: green boltergiller (Potamocetus viridis) smaller fish reaching only two-meter length. It differs in richer branchial stamens allowing filtering from water phytoplankton – the main food of this species. The body of this fish is higher and also has greenish colouring.

Deadly phyllomormyrus (Phyllomormyrus lethalis)
Order: Elephantfishes (Mormyriformes)
Family: Elephantfishes (Mormyridae)
Habitat: Zinj Land, steady flowing rivers and lakes.

Picture by fanboyphilosopher

Till the evolution process the role of adaptations produced by ancestors of any species of live organisms can vary strongly. For example, leaves of plants may turn to spikes, and stalk fulfills the function of leaves. When any plant loses petals, but later comes back to pollination with the help of insects again, floral bracts become bright like petals. Such phenomenon of function change is not a rarity in nature.
At African elephant fishes till the evolution the adaptation was developed for orientation in space in conditions of bad visibility – fishes had got ability to develop faint electric field, and began to define the presence of other objects near to themselves by its changes. Such attribute during the evolution process appeared repeatedly at various species of fishes, therefore the development of electric bodies at elephantfishes does not look something oustanding. When the East African subcontinent (Zinj Land) had separated from the continent, these fishes began to evolve independently of continental species. In reservoirs of Zinj Land the special ecosystem had formed, where the original species of elephantfishes became one of top predators. It has developed special hunting tactics getting food – small schooling fishes and tadpoles.
These species of elephantfishes is named phyllomormyrus (“leaf-like Mormyrus”) for the special body shape and coloring. This fish has cryptic coloring and shape which simulates rotting leaves very precisely. High rhomb-like body of fish is compressed from sides; it is about 20 cm long and colored brown with yellowish spots. Along the side rough light strip stretches. On back and anal fins there are rough dark brown borders similar to rotten edges of leaves of any tree. The edge of back fin, pectoral fins and tail of fish are completely transparent. Eyes of phyllomormyrus are also disguised – iris of eyes is brown with grey “marble” pattern masking the eye at the background of body colouring. The snout of phyllomormyrus has the lengthened shape characteristic for these fishes, and simulates a leaf petiole. It is very long, and also makes about one third of general length of fish. On the tip of snout there is small mouth with short appendage on lower lip. The male of this species does not differ from the female in colouring; it is only smaller a little than the female.
The hunting tactics of phyllomormyrus combines tactics of South-American fishes of Holocene epoch known to people: leaf fish (Monocirrhus polyacanthus) and electric eel (Electrophorus electricus). This species of elephantfishes eats small animals, preferring tiny schooling vertebrates. This predator creeps to fry or tadpole school using cryptic colouring. The shape of fish simulates leaves of a tree beginning to rot so well that it misleads even the most cautious fishes. Hunting phyllomormyrus is slowly swimming to planned prey, moving by transparent fins. For most persuasiveness fish can swim in any position, keeping body obliquely or even laying on the side. Appearing among fry or tadpole school the fish suddenly strikes them by electric impulse. Stunning prey, fish can emit one by one up to four electric impulses in succession. After that fish simply gathers paralysed catch by proboscis from the bottom. If necessary the phyllomormyrus gives additional electric impulses, paralyzing animals trying to escape from it. Phyllomormyrus also eats larvae of insects, searching for them in thickets of underwater plants.
This fish is a single predator. Each individual occupies the certain site in shallow waters overgrown with plants. Large driftwood and bushes of water plants serve as marks of territory borders. When two fishes meet at the border of territory, they exchange series of faint electric pulses, distinguishing each other and estimating physical condition of the contender. Usually young fishes live at boundaries of sites of adult fishes, avoiding an opportunity of meeting the adult individuals. These fishes can not injure each other by stings - mouth at them is too small for it. But the adult fish can paralyze and even kill young individual of this species by electric impulse.
The spawning of phyllomormyruses begins with approach of rainseason. Pairs at this species are formed of adult individuals living at next sites. Before the spawning male and female exchange electric pulses in special rhythm which is analogue of courtship dance. For this purpose partners rise under floating plants in parallel to each other, and emit a series of electric impulses. First male and female do it alternately, and then pulses become simultaneous. Such feature of behavior synchronizes processes of roe ripening. Prespawning games proceed till approximately day and night. For spawning fishes build a nest of floating long-steme plants. They weave plants to dense tangle among thickets, and get into it together to spawn large eggs.
In clutch of phyllomormyruses it may be totally more than three hundred large eggs. The male protects nest against possible predators with the help of electric impulses. At this time it eats almost nothing, and only occasionally catches prey had casually appeared near the nest. The egg incubating lasts about three days, and two more weeks larvae not able to swim sit in nest. When fry starts to swim and leaves the nest, male ceases to protect the posterity. Young fishes usually keep in rich thickets of plants where adult fishes of this species can not make the way. To the end of first year of life young fishes reach the length 4-5 cm, and at the third year of life at length about 15 cm they already start to breed.

Nile iniorhynchus (Iniorhynchus niloticus)
Order: Mormyriformes (Mormyriformes)
Family: Elephantfishes (Mormyridae)
Habitat: Africa, the Saharan Nile.

Picture by Andrey, colorization by Biolog

Elephant fishes were a very characteristic component of the African ichthyofauna. In the Neocene, some of the species of these fish remained on the East African subcontinent (Zinj Land) that split off from Africa and evolved independently of African species. In the rivers of Africa in the Neocene, peculiar species of mormyrid fishes also evolved, having no analogues in the ichthyofauna of the human epoch.
One of the species of African mormyrids is the largest representative of the family. It is Nile iniorhynchus, a fish about 2 meters long. It lives in the Saharan Nile and Niger from the upper reaches to the mouth, preferring overgrown backwaters with a slow current. It has related species in the Congo basin, but none of them reaches such size.
Iniorhynchus is very similar to a dolphin in its size and elongated snout. The eyesight of this species is poor – often the iniorhynchus has to swim in water that loses transparency due to silt suspension or multiplying microscopic algae. In addition, twilight and nocturnal activity is characteristic of iniorhynchus. In this regard, the coloration of this fish is not bright: on a silvery background with a greenish tinge, 5-7 vertical stripes of dark gray color stretch, entering the dorsal and anal fins. The female and male do not differ in color; the male is only slightly smaller and slimmer than the female.
The eyes of this fish are very small, its vision is weak: the fish is short-sighted and is only able to detect the outlines of objects that are more than 3-4 meters away from it. But poor eyesight is fully compensated by the presence of a highly sensitive electrolocator inherited from its Holocene ancestor, one of the numerous species of elephantfish. At the base of the tail, there is an area of modified muscle tissue generating an electric field, and on the body surface (mostly on the head and on the elongated snout), there are numerous electroreceptors. Also, this fish has a well-developed sense of smell and has a highly sensitive lateral line forming several branches on the head skin. The electric field generated by this fish is quite weak. But if necessary, iniorhynchus can generate stronger single electrical impulses, which are used for protection (they are not lethal, but sensitive to most predators), as well as in tournament fights between males.
In this species, brain reaches exceptional development: its ratio to body weight is almost like in mammals. However, unlike them, this fish has the most developed cerebellum and stem parts of the brain. Nevertheless, by the standards of fish, this species is remarkable in its high intelligence. Iniorhynchus in a school are able to communicate with each other using weak electrical impulses; it is especially pronounced during the feeding: if one iniorhynchus finds food, the whole school gathers to it very soon.
Unlike Holocene benthophagous mormyrids, iniorhynchus switched to feeding mainly on small schooling river fish. These fishes hunt mainly at night and at dusk, but in muddy water they can be active during the day. Swimming in small schools and acting together, iniorhynchuses are able to entrap prey, driving it into a dense shoal. Proboscis-like jaws instantly suck in any small fish – the mouth of this fish is tube-shaped when opened. However, this species has not lost the ability to feed on bottom animals – a sensitive snout covered with electro- and olfactory receptors is very convenient for digging silt.
During the spawning season, the female builds a “nest” in dense underwater vegetation, bunching long stems into a spherical pile. Partners find each other by specific electrical impulses, which pattern serves as an indicator of readiness for reproduction. During spawning, the pair makes a through hole in a pile of plants and, swimming through the nest, leaves eggs on its inner side in some repeating acts. The fecundity of this species is about 100 thousand eggs. Iniorhynchus tends to take care of its offspring: the female guards the eggs until the fry hatch and stays close to the nest until the fry leave it. Juveniles usually swim in schools in underwater thickets. If the fry are in danger, then the electric “cries of panic” emitted by them attract adult individuals (not necessarily parents), who usually drive away the predator.
Sexual maturity comes at the 5th year of life, and the total life expectancy can reach 50-60 years.

This fish species was discovered by Andrey, a forum member.

Ice galaxia (Antarctogalaxia cryoresista)
Order: Galaxiiforms (Galaxiiformes)
Family: Galaxias (Galaxiidae)
Habitat: fresh waters of Antarctica.
Antarctica is a continent which nature had gone through catastrophic changes in late Cenozoic. The severe congelation had held down continent for millions years by ice layer of more, than one kilometers thick, having completely deprived this ground of vegetation and fresh water. In Holocene the nature of this continent was presented only by sea animals dependent on efficiency of ocean, and several species of tiny terrestrial invertebrates.
In Neocene, due to climate warming, glaciers of Antarctica had started to thaw. The significant part of continent had exempted from ice, but in polar area still there is a glacial cover. But the edges of continent directed to Indian Ocean and Australia, are covered with meadows of graminoids and sedges. In spring, when snow thaws, meadows become covered by circuit of lakes and bogs. Besides on central glacier short rivers spring. In them an interesting ecosystem had formed – the primal freshwater fauna of fishes was destroyed by a congelation, and various larvae of dragonflies have partly replaced small fishes live in the majority of temporary and constant reservoirs. Sea fishes come into lower reaches of Antarctic rivers, but they do not live in fresh water constantly. However some descendants of sea fishes passed to life in fresh water. It is rather difficult step – in Antarctica extreme conditions of an inhabiting dominate. In frosty winter rivers of Antarctica become covered by thick layer of ice, and shallow standing reservoirs may freeze up to the bottom. But all the same, as soon as ice thaws, in the rivers of Antarctica it is possible to see fishes.
Long-bodied fishes about 20 – 30 cm long slide in ice-cold water among stones. At them there is rounded in section eel-like body supplied with short fins. The skin of fish is lack of scales, covered with layer of slippery slime due to what fish freely rummages in stones, not being afraid, that it may be pressed down. Colouring of this fish is brown with numerous green speckles. This inhabitant of Antarctica is named ice galaxia, and it belongs to group of fishes very characteristic for southern hemisphere. In prehistoric times galaxias, obviously, lived in Antarctica before the continent was buried under ice cover. In Neocene descendants of one species of these fishes (possible, South-American or Tasmanian one) had conquered the continent “fishless” earlier.
Ice galaxia almost constantly lives in fresh waters of Antarctica - in rivers, lakes and bogs. It eats larvae of numerous Antarctic species of dragonflies. This fish can catch swimming larvae in thickness of water, but prefers to dig ground by flattened head in searches of sluggish creeping larvae of large species of dragonflies.
For Antarctica the seasonal climate with sharp difference between winter and summer temperatures is characteristic. Though Neocene is rather warm epoch, Antarctica still is near South Pole, and it is only slightly warmed with sea currents from equator. Therefore in winter ice galaxias put on trail on durability – they should resist to all-permeating rigorous cold. These fishes do not try to escape in warmer places (for example, in sea). They continue to live in the same place where they lived before colds. When frosts lock the surface of reservoir, fishes dig in silt, plaiting in tangle of several tens individuals and plentifully secreting slime. Such tangle of fishes is surrounded with viscous mucous mass which has two important qualities – antifreeze and antiseptic. It interferes the freezing of integuments of fishes, and does not enable parasites to attack hibernating fishes. In winter at weakened fishes in collective hibernation wounds heal easier, and individuals struck by ectoparazites recover. In deep whirlpools fishes do not dig in ground, but also surround itself with slime. This way fishes hibernate more successfully – even if ice is formed on the surface of common mucous cover, fishes will not be injured. And even if the tangle of fishes will freeze in thickness of ice, inside it all the same semi-liquid slime remains.
Ice galaxia spawns in lower reaches of rivers and at the sea shallows. In spring till the high water time fishes had survived in wintering, migrate to lower reaches of rivers by large shoals. If fishes hibernated in standing reservoir, they all the same aspire to reach the sea. While night replaces day, fish creeps out of water and creeps by ground to the nearest river, being guided by smell of river water. Males arrive to breeding bottoms the first. Having felt brackish water, they get courtship dress. In breeding-dress at the male green speckles in forward part of body turn golden, and iris of eyes brightens. Males begin courtship demonstrations in places well protected from local fish-eating birds – yellow-headed divesparrow and large penguigulls: among brown algae where birds do not swim. They gather schools, and while there are no fish-eating birds around, demonstrate themselves in shallow water. At the slightest sign of danger they hide among seaweed and turn dull.
When females come, males change. Any care is lost, and rough spawning begins. Schools of males and females join, and leave a trace of pale soft roe and small translucent eggs. At this time they are not afraid neither birds, nor predatory fishes, absorbed by the purpose of breeding. Fishes scatter eggs at the bottom, and it is the limit of their care of posterity. After spawning schools of ice galaxias remain in lower reaches of rivers till some days, restoring forces. Strongest individuals spawn once again, though a repeated spawning is not as active, as main one.
Young fishes spend first two years in river estuaries which do not freeze – they are too small to resist to cold. It is easier to hibernate to large fishes, and small fishes often freeze in ice and freeze through, that results in their death. Having reached approximately 2/3 of the size of adult individual, ice galaxias rise upstream and settled from river mouth to fresh waters of continent. Young fishes rise against the current in common with adult individuals coming back from spawning. It will pass about 2 – 3 years, and they will mature and can take part in spawning.
Long growth of ice galaxia is compensated by enviable longevity – cold winters as if brake ageing of fish organism, “preserving” it approximately for half-year. For this small species of fishes the age of 40 years is usual term of life, and occasionally even 50 – 60-years old “patriarchs” are found.

Great Murray Perch-Galaxias (Megalogalaxias rex)
Order: Galaxias (Galaxiiformes)
Family: Megagalaxias (Megagalaxiidae)
Habitat: Murray River in southern and south-eastern Meganesia, deep, slow moving river channels with snags and thickets of vegetation.
The Murray River, during the Holocene occupation by man on earth, suffered agricultural degradation and invasion by introduced species. Dominant predators such as the Murray Cod (Maccullochella peelii) not only suffered from this, but also from fishing, and they eventually became extinct.
Unpretentious species came to replace it in the Neocene, descendant of Common Galaxias that had formed new family of large predators – Megagalaxiidae. This fish is generally like a large perch in shape, but slightly more elongate, body is round in cross-section, partly cylindrical, and the head is a broad scoop with a large mouth bearing rows of sharp teeth, lower jaw protrudes slightly. Soft dorsal and anal fins are low and round being relatively large, pectoral and pelvic fins are also large and rounded. Caudal fin is broad and round. Coloration is an overall mottled greenish brown, with many small dark spots, the fins being darker than the body. This fish is quite large, reaching up to 1.5 meters in length and weighing up to 45 kilograms.
They are solitary by nature, and feed by ambushing smaller fish, frogs, crustaceans, small vertebrates, and the young of water birds. They prefer the security afforded by snags and thickets of underwater vegetation, but can swim well in open water as well.
Sexual maturity is reached at about 6 years, females that are of larger size produce the most eggs, up to 15000. Males and females congregate at river mouths, where many females attach their abundant eggs to aquatic vegetation, fertilized by many males, which then leave. Spawning occurs in the spring, larvae drift in estuaries and when they become small juveniles (5-10cm) they migrate back into the mid reaches of the river. These fish do not die after spawning, and may spawn many times in their lives; lifespan is up to 50 years.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Eyre Perch-Galaxias (Galaxiharpax atrox)
Order: Galaxias (Galaxiiformes)
Family: Megagalaxias (Megagalaxiidae)
Habitat: Waters of Eyre Gulf in southern Meganesia, open water.
Freshwater fish of Meganesia suffered greatly during the Holocene, at the hands of introduced species, and agricultural degradation of waterways. Species adapted to cope with different water conditions, salinity, stagnant or silty, prevailed, among them native Galaxias, which we see now in the Neocene.
Along with some others, including freshwater ones, this fish is part of the subfamily (Percogalaxiinae), forms converging on perch and other large predators in shape.
This fish is a rather large predator found in Eyre Gulf, ranging from 50 to 80 centimetres long. Unlike its immediate ancestor, it is an active arch-predator, with a large, triangular caudal fin, pointed anal and soft dorsal fins, and a thick, hydrodynamic shape, somewhat like a snapper (Lutjanus), but more elongate. Jaws are large and slightly projecting, giving a pointed shape; teeth are large, trenchant and conical. This fish swims actively in the water column, prowling in search of smaller fish and shrimp, which it catches by chasing over some distance. Colour is an overall pale olive hue, darker on extremities, with a prominent silver sheen.
It is active during the day, and into twilight, eyes are large and vision is keen. Being solitary by nature, others are only tolerated at breeding time, and during large accumulations of prey species.
Breeding occurs in April to June after these fish migrate up to where the gulf meets the Murray River. Here in brackish water, thousands of eggs each are laid by each female, all at once, which are then fertilized by large groups of males, gestation of these eggs reaches about 2 weeks. Larvae after hatching are washed out into the gulf, at this stage about 8mm long, they eventually mature into juvenile fry at about 5cm long. At the juvenile stage they form large shoals, until they begin to show the predatory features of the adult, after which they disperse. Lifespan can be up to 20 years, mortality does not occur after spawning, and adults may spawn multiple times.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Eyre Wormtail Galaxias (Tantalogalaxias serpens)
Order: Galaxias (Galaxiiformes)
Family: Megagalaxias (Megagalaxiidae)
Habitat: Waters of Eyre Gulf in southern Meganesia, sea floor in shallow waters.
Australian freshwater fish during the Holocene suffered somewhat due to environmental degradation and agriculture, as well as game fishing and introduced species. But some native species, especially those able to tolerate a range of water salinities prospered, among them galaxias (Galaxiidae), sleeper gobies (Eleotridae) etc. The creation of Eyre Gulf, from the inundation of the inland salt-pan lakes of lowland southern Australia, created the opportunity for Galaxias to speciate into numerous specialised forms.
The Eyre Wormtail Galaxias is middle-sized, reaching a maximum length of 1 meter not counting extension at the end of the tail, body is slender and elongated. It is a bottom-dwelling ambush predator, laying in wait buried in the substrate of the sea floor. Jaws are elongated and strong, resembling the mouth of an eel, but with large lips covering the long pointed teeth. Eyes are set forward, fish sits in wait buried with top of head protruding from the sea floor. Arrangement and size of fins generally resembles those of its Holocene relatives, except that adipose and dorsal fins are set well back towards the end of the body, paired fins are relatively small and rounded. Caudal fin is low, somewhat long, and the upper-most fin ray is greatly elongated, about 30 centimetres long, with a pink fleshy lure at the end.
This fish sits in ambush in order to snatch prey; body is buried posed in a “horseshoe” shape with head and tip of tail close to one another. The long tail-lure protrudes some distance, and mobile lure is agitated and wriggled, to attract smaller fish. Agitated lure brings prey within close distance to the head, and prey is seized in its jaws.
It is active during daylight, particularly the afternoon, it stays waiting in one spot in order to hunt, but when resting, whole animal is buried.
Breeding occurs between April and June, individuals travel in large numbers to the mouth of the Murray River. In the lower reaches of the river, large groups of females deposit their eggs at once, thousands laid by each gravid female. Awaiting groups of males spread clouds of milt to fertilise the eggs, which hatch after 5 weeks. Tiny larvae are washed out into the wider part of Eyre Gulf, at this stage they are only 9 millimetres long, maturing into fry at about 8 centimetres long. Young fry swim in large shoals, and after growing longer, start to exhibit physiology and habits of the adult. Lifespan reaches up to 18 years, mortality does not occur after first spawning and individuals may spawn up to 3 times in their life.

This fish species was discovered by Timothy Morris, Adelaide, Australia.

Golden Angel-bait (Galaxiiangelis aureus)
Order: Galaxiids (Galaxiiformes)
Family: Angel and Tetra Galaxias (Galaxiiangelidae)
Habitat: Eyre Gulf, thickets and tangles of underwater vegetation.

Picture by Lyagushka

Adaptive radiation is a common phenomenon, especially after the extinction of a greater part of certain competitors. So we see the extinction of marine fish at the border between Holocene and early Neocene, with different forms coming to replace them. In the Eyre Gulf, such ornate forms are the Angel-bait, (Genus Galaxiiangelis).
These fish descend from the Common Galaxias (Galaxias maculatus), a widespread and successful fish with both freshwater and saltwater descendants in Neocene. This form greatly differs from its ancestor, being an almost diamond body shape with large, sickle-shaped dorsal and anal fins, almost resembling reef dwelling and freshwater “angelfish”, hence its name. Reaches a body length of 8 to 10 centimetres, and body with fins are about 7 centimetres tall.
This schooling fish is shy and tends to hide in thickets of marine plants, its diamond shape compensates for its relatively slow swimming speed, making it less easy for predators to swallow. It is a bright, canary yellow colour, with a silvery sheen, and striped on the fins and body with contrasting black. Face is short, mouth is somewhat pointed, with small sharp teeth, its diet mainly consists of small crustaceans and larvae, including those that are gleaned from underwater vegetation or rocks, some encrusting algae is also consumed.
Breeding occurs in the wet season, schools merge together and females lay large masses of eggs on submerged vegetation, close to where the gulf meets the sea, Many males fertilize the eggs, which gestate for 1 week. Tiny larvae are washed out to sea, and will return in large shoals to the gulf when they become juveniles of about 2 centimetres long.
Related smaller form is the Red-ticket Angel-bait (Galaxiiangelis ornatus), distinguished by smaller size (only 5 centimetres long) and bright red coloration, stripes and spots on body are a rich, dark blue.
A larger, slightly more predatory form is the Silver Angel-bait (Galaxiiangelis spectra), reaching up to 18cm long and aggregating in smaller groups. More aggressive by nature, it seeks out somewhat larger prey and may eat fish and shrimp. Its colour is an all-over silvery bronze with a reflective sheen, banded and spotted with contrasting black.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Ichthyophyseter, cachalote fish (Ichthyophyseter theutiphagus)
Order: Tarpons (Elopiformes)
Family: Cachalote fishes (Ichthyophyseteridae)
Habitat: temperate and cold waters of all oceans, depths from 100 up to 2000 meters. At night individuals from the populations living in the top layers of ocean may rise almost to water surface.

Picture by Alexander Smyslov

Overhunting and pollution of ocean had resulted in sharp decrease of number of cetacean population, including odontocetes feeding at the great depths – sperm and bottlenosed whales. Populations of these animals appeared too small in order to restore the species of these mammals in former number. This event had resulted in growth of number of cephalopods – the basic prey of these whales. In early Neocene squids had made serious attempt to press fishes in habitats of open ocean. They had occupied ecological niches of medium-sized predators, and some of them became very large animals. To reply to the burst of number and variety of squids among fishes the species capable to compete to them, and even to attack squids began to evolve. Among them false swordfishes, capable to catch up even the fastest squids, had appeared. And other species had staked on strenght and had turned to specialists in large squid hunting. The cachalot shark (Physelache planicephala) from Northern Atlantic and also cosmopolitic mesopelagic cachalote fish, or ichthyophyseter, belong to such species. It descends from one species of tarpons (Megalops) – representative of low-specialized group of osseous fishes. Due to unpretentiousness and ability to live in water of various degrees of salinity tarpons managed to survive in epoch of anthropogenous pressure, and after human disappearance had made a number of successful attempts to manage pelagic habit of life.
The body length of this species is up to 6 – 7 meters; it is one of the largest osseous fishes of Neocene. The body of ichthyophyseter has a shape typical for tarpon fishes – fish resembles huge herring with disproportionately large head reaching the one fifth of a body length of fish.
Ichthyophyseter is bad swimmer. This fish is able to do short fast throws but swimming to long distances is an excessive task for this predator. Unpaired fins of this fish are shifted back. Back fin is pointed, and tail fin is wide and forked. Body is covered with tiny scales deeply immersed in skin. Because of it the skin of fish seems rough to the touch. Skin has dark grey color; fins are transparent. Peritoneum is also transparent, and swallowed prey is visible through walls of stomach.
Muscles of ichthyophyseter are rather flabby and soft. The most part of time fish passively floats in water due to fat with which its muscles and skeleton are impregnated. Eyes of ichthyophyseter are completely reduced. Even traces do not remain from them; the optic nerve is also reduced. In life of fish sight is functionally replaced with seismosensoric feeling: at ichthyophyseter bodies of lateral line are well advanced. They form dense circuit on head and the dual lateral line along the body. Sense of smell of ichthyophyseter is also very keen. Large nostrils have the unusual shape – they are extended to long grooves, are arch-like bent upwards and stretch from tip of muzzle up to the place of former eye-sockets.
Teeth of ichthyophyseter are numerous and similar to nails – they are very thin and long. Some hundreds teeth grow not only at the edges of jaws, but also on the palatal bones and on edges of tongue. Small peaked teeth also cover a surface of tongue. The main task of such teeth is not to cut flesh, but to keep slippery and flabby body of squid – the basic prey of ichthyophyseter.
This species lives mainly in depths of ocean. In Atlantic ichthyophyseter competes to cachalote shark and consequently keeps in depths. In other parts of area this fish frequently rises to the top layers of water, and it happens, that the heavy gale casts such fishes ashore.
As a meeting of such fishes in depths is rather rare event, in breeding physiology of ichthyophyseter the essential changes take place. This species is hermaphroditic; each individual is capable to produce simultaneously male and female sexual products. Fertilization is carried out with the help of cloaca capable to turn outside. Self-fertilization is possible only in extreme cases, and usually two sexually mature individuals mutually fertilize each other. Sperm is kept viable for a long time in distal part of ovoduct. At the moment of egg spawning spermatozoids leave in water, turn more active and fertilize eggs. Eggs are spawned as a long slimy cord that facilitates care of posterity: fish at once takes the fertilized eggs in mouth and bears clutch within several days. Spawning takes place repeatedly within one year.
The characteristic for tarpons leptocephalus larva of prolonged leaf-like shape hatches from egg. It leads pelagic way of life and has well advanced eyes and wide mouth with pointed teeth. Leptocephali of ichthyophyseter live in top layer of water and eat young ones of other species of fishes and pelagic invertebrates. Cannibalism is also characteristic for them. At the length of about 4 – 5 cm metamorphosis begins: the reduction of eyes and increase of mouth take place, body turns narrower and shorter. Fry of ichthyophyseter lives at the depths of 30 – 50 meters and eats mainly crustaceans and small fishes. As fish grows, the reduction of eyes proceeds further and fish passes to life in depth. Its diet changes, and it passes to feeding on cephalopods. At the age of five years it reaches the length of two meters, and fish grows up to maximal size at the age of twenty years. Life expectancy of ichthyophyseter reaches 60-70 years.

Rhomb-tailed cryptocleidichthys (Cryptocleidichthys rhombocaudis)
Order: Tarpons (Elopiformes)
Family: Cryptocleidichthyids (Cryptocleidichthyidae)
Habitat: Pacific Ocean, depths from 200 to 500 meters.

Picture by Lyagushka

Fishes of the Elopiformes order did not stand out against the background of the more noticeable and numerous orders of fishes inhabiting the oceans. But at the turn of the Holocene and Neocene, in the era of mass extinction of marine ichthyofauna, they had got a chance to occupy new ecological niches and increase their diversity. One way of their evolution was pedomorphosis – the extension of the larval stage of development with the reducing of the adult stage and the preservation of larval features of the anatomy for life. Similar to leptocephalus, the larvae of Elopiformes became the basis for the evolution of a new fish taxon with unique structural features. Representatives of pseudoleptocephalids occupy a variety of ecological niches in the ecosystems of the open ocean, most of them being planktonic forms. Some of them have switched to a different way of life, turning into deep-sea carnivores. Cryptocleidichthys is one of these fish species; it lives on the upper limit of the mesopelagic zone and never rises to the surface.
The body of this fish has a very peculiar shape, in which the original leptocephalus-like type of anatomy is hardly guessed. The front part of the fish’s body is narrow, long and flexible, capable of making movements in various directions with significant amplitude. The back half is deep and muscular, less mobile compared to the front one; the body of the fish looks as if composed of two completely different halves and slightly resembles the body of a plesiosaur (hence the name). The head is narrow, with an elongated snout and elastic ligaments between the jaw bones. The teeth are long, pointed, slightly curved, sticking out of the closed mouth. The mouth can open very wide and swallow prey larger than the head of the fish itself. The eyes are small; the vision allows it to distinguish the glowing emitted by other organisms. A network of sensitive lateral line channels is developed on the head and the front part of the trunk. The body is covered with scaleless skin of pale gray color. The length of an adult one reaches 60-65 cm .
Paired fins are greatly reduced: only small skin folds remain from the pectoral fins; pelvic fins are absent. The unpaired fins are strongly shifted backwards and merge into a unite structure bordering the rear part of the body. The cloaca is shifted to the border between the anterior and posterior halves of the body, and the stomach, on the contrary, is strongly shifted back and is located behind the intestine, which makes a loop along the abdominal side of the body.
The normal body position of this fish is vertical, head up. Due to the undulating movements of the unpaired fins, the fish can move up and down, but when frightened, it takes a horizontal position and swims away, writhing with its whole body. The position of the body is associated with the peculiarities of lifestyle. Cryptocleidichthys is a solitary predator and feeds on schooling crustaceans, cephalopods or fish. Plunging from the bottom up into a school of small animals, the fish bends the front part of the body in various directions and catches its prey. At this time, the massive back of the body serves as a support, allowing it to make precise movements.
Sexual dimorphism in this species is poorly expressed: females are only larger than males. Mating behavior is primitive: fishes just stay vertically and parallel to each other for a while, contacting via undulating body movements. Synchronizing their behavior, the fishes spawn a portion of eggs and soft roe into the water. There are up to 200 thousand very small eggs in a clutch, a female makes up to 5 clutches per year. The larva develops in plankton in the upper layers of water. Sexual maturity comes at the age of 4-5 years, life expectancy is up to 40 years.

Perfect jellyfish king (Cephalanguillops magnificus)
Order: Tarpons (Elopiformes)
Family: False leptocephali (Pseudoleptocephalidae)
Habitat: Pacific Ocean, tropical, subtropical and temperate zones of both hemispheres, upper layers of water down to a depth of 50 meters.
At the boundary of the Holocene and Neocene, during the “plankton catastrophe”, a significant number of fish taxa died out, among which there was an eel order. But the distant primitive relatives of eels – elopiform fishes resembling large herring – have persisted. Due to the development in coastal waters, they managed to survive the “plankton catastrophe” that affected the ecosystems of the open ocean, and after the stabilization of natural conditions, they returned to the oceans in a new capacity – as pelagic fish. One of the groups of elopiform fishes followed the path of prolongation of the larval stage of development until the loss of the adult stage and reproduction at the larval stage. The result of the evolution of the larval stage of this group of elopiforms is the Pseudoleptocephalidae family, which includes a variety of eel-shaped fishes, most often with a ribbon-like body, strongly compressed from the sides. They are inhabitants of the open ocean and are almost never found near the shores. Some representatives of the pseudoleptocephalids have a bizarre appearance and are differ strictly from the adult stages of ancestral forms.
In the tropical zone of the Pacific Ocean, one of the most bizarre representatives of this group is found – the perfect jellyfish king. It is a very large eel-shaped fish with a deep, laterally compressed body; the length of an adult is up to 4 meters. Representatives of this species have a short, vertically elongated head with a deep convex forehead; the front edge of the head is almost vertical. The large eyes are shifted to the lower half of the head. The fish has a small retractable mouth with a highly oblique cleft and a “ferocious” expression on its muzzle. Due to the movable ligaments between the bones, the mouth can extend to a tube that allows it to suck in food objects. The teeth are very small, bristle-shaped, allowing it to hold animals with soft covers without tearing them.
The body of the perfect jellyfish king is very elongated, gradually tapering to the tail. The caudal fin is reduced to a thread of two fused fin rays; it merges with the dorsal and anal fins, which stretch along almost the entire body. The anterior rays of the dorsal and anal fins are very long and elastic; the bases of these rays on the dorsal fin merge with the spinous processes of the vertebrae. At the tips of the rays, there are skin “flags” of a rounded shape. The intestine stretches along the lower side of the body. The anus is shifted to the chest, almost to the level of the posterior edge of the operculi. Paired fins are greatly reduced. The skin of this fish is scaleless, smooth and covered with a layer of slime containing an inhibitor for stinging cells of coelenterates. The general color of the body is greenish-blue with a strong iridescent sheen, the “flags” on the fins are black with a white edge.
Perfect jellyfish king lives in the open ocean, far from the coast, and feeds exclusively on soft-bodied planktonic invertebrates, being often found in congestions of jellyfish (hence the name). The inhibitor accumulates in the body slime individually, depending on the frequency of encounters and the species composition of the jellyfish that the fish feeds on. Since jellyfish and tunicates represent a low-nutritious food source, the fish feeds almost continuously all day, slowly swimming in the water column due to undulating movements of unpaired fins. The fish sucks the prey in whole, and tears off pieces from large jellyfishes. This fish receives a significant part of the nutrients from the prey swallowed by jellyfish.
The life cycle of the perfect jellyfish king is very peculiar. Despite its size, this fish grows very quickly and does not live longer than 3-4 years, while reproducing only once in a lifetime. Spawning time is extended for the whole year, but on the northern and southern edges of the range, breeding is timed to the beginning of summer. Mature fish stop eating and undergo profound physiological changes: the intestines degrade, the gonads grow, and the body begins to shorten. The female develops a large number of eggs – up to 50 million eggs. The male’s olfactory rosettes increase and he is actively searching for a female. Ready-to-breed fishes get a more intense coloration and find each other by smell. They spawn their eggs in the water column after a simple mating ritual involving swimming side by side together; the eggs develop in plankton within 24 hours. After spawning, the fish's body rapidly degrades, and it literally decomposes alive – sometimes the body breaks up into several pieces while the fish is still showing signs of life.
The larva is a typical leptocephalus feeding on small invertebrates and absorbing organic substances through thin body coverings. As it grows, it gets pigmentation and at the age of six months resembles adults in its appearance, but being only 20-22 cm long.
In the tropics of the Atlantic Ocean, a close species lives – splendid jellyfish king (Cephalanguillops splendidus). It differs from the Pacific species in a more expressed cyan body color, which turns dark blue with white specks on the back. The “flags” on its fins are green with black tips.

Gigantic jellyfish king (Xenanguilla regalis)
Order: Tarpons (Elopiformes)
Family: False leptocephali (Pseudoleptocephalidae)
Habitat: temperate regions of the oceans of the southern hemisphere.
The evolution of the elopiform fishes towards pedomorphosis proved successful: it led to the appearing of a new group of pelagic planktophagous fishes in the World Ocean. Many species of this group represent small forms, often glass-transparent and very fragile, but among them there are also true giants, as well as owners of bright coloring or iridescent shine of body coverings. Gigantic jellyfish king – a giant species of “adult leptocephalians” of the order Elopiformes – occupies a special place among them. By its size, this animal belongs to the number of largest fish species of the Neocene, although many species of fish exceed it in weight. The length of an adult of this species reaches 7 meters. Gigantic jellyfish king has a ribbon-like body that is of equal depth for most of the length of the fish and gradually tapers to the tail only in the rear quarter. The caudal fin of this fish consists of two elongated and fused fin rays about half a meter long. The dorsal fin stretches along the entire upper edge of the body from the head and fuses with the reduced caudal fin. The anal fin stretches along the posterior two-thirds of the length of the fish. The intestine stretches along the underside of the body, making a loop and opening with an anal opening in the middle between the throat and the beginning of the anal fin. The body of the fish is covered with bare skin with a thick layer of slime. The general coloration of the body is greenish-white; from the head to the tip of the tail along the middle line of the body a narrow strip with an intense silvery sheen stretches. The edges of the body are translucent, the unpaired fins are transparent. The pectoral fins are greatly reduced and are not visible from the outside.
Gigantic jellyfish king has a short, deep head, strongly elongated vertically. This species is zoophagous, and a large, highly oblique mouth helps it to swallow large prey. The mouth cleft is directed almost vertically, and the tip of the lower jaw is above the level of the upper edge of the eye. The teeth of this fish are needle-shaped and very strong, slightly bent back.
Gigantic jellyfish king swims, wiggling in a horizontal plane, but most often it slowly drifts in the water column, stretching its body and moving by undulating movements of unpaired fins, and waits until the prey approaches the distance of a short accurate rush. This species feeds mainly on soft-bodied planktonic organisms, and occasionally eats crustaceans. The basis of the diet consists of large siphonophores and jellyfish, and these fishes are often found in their congestions (hence the name). Like smaller related species, gigantic jellyfish king develops immunity to the venom of the coelenterates. But this species can also dive to a depth of 200 meters in search of food. At depths, this fish attacks slow and soft-bodied pelagic octopuses and squids.
The musculature of this fish is watery and relatively weak, so when a storm approaches, this fish sinks into the lower layers of water. Gigantic jellyfish king grows rapidly and matures in 3-4 years. At the 7th year of life, the fish reaches the average length of representatives of this species. Unlike small related species, this fish breeds every year. The male differs from the female only in a more graceful constitution. Courtship includes the male’s chase of the female, touching the partner’s body and mild bites that the male inflicts on the anal fin of the female. There are up to 40 million very small eggs in the clutch; spawning occurs twice during the summer. Eggs develop in plankton for 20 hours; the fry are ribbon-shaped with blunted tail fins and narrow heads; their appearance changes greatly as they grow.

Thin diamond glassfish (Platyrhombus angustus)
Order: Tarpons (Elopiformes)
Family: False leptocephali (Pseudoleptocephalidae)
Habitat: Atlantic Ocean, subtropical and temperate regions.
Elopiform fishes managed to persist during the “plankton catastrophe” due to the peculiarities of their life cycle: their development took place mainly in coastal waters and estuaries, which were almost unaffected by the events that destroyed a significant part of the inhabitants of the open ocean. During the formation of the biocenoses of the open ocean, the elopsiformes were among the main candidates for the settling of this area. The evolution of one group of these fishes followed the path of preserving of larval features in adulthood. In fact, these fishes turned into adult leptocephalic larvae and formed a separate Pseudoleptocephalidae family.
For the most part, “adult leptocephalians” have developed a ribbon-like shape, but among pelagic species, there are deep-bodied forms with relatively short and strongly laterally compressed bodies that form the genus Platyrhombus. These are open ocean fishes about 80-120 cm long. In diamond glassfishes, body is deep in the middle part and strongly narrows to the head and tail. The head is relatively small, with a wide toothy mouth; the caudal fin is rounded and shortened. In the anterior part of the dorsal and anal fins, the rays are elongated compared to others. They form outgrowths that complement the rhombic body shape of these fishes. One of the most common species of this group is the thin diamond glassfish inhabiting the Atlantic Ocean north of the equator.
This fish is found in the open ocean from the surface to depths of 50-70 meters, preferring to keep in congestions of plankton. The consistency of the soft tissues of these fishes is very delicate, and the skeleton is flexible and poorly calcified. The soft texture of the tissues gives this fish one advantage: it can regenerate body parts lost after attacks of other planktonic predators. Even a tail with a caudal fin regenerates completely, differing from the original one only by a slightly smaller size. The body coloration of this species is almost completely absent: only the peritoneum is shielded by a silver lining and there are separate black spots on the dorsal fin and in the upper part of the body. The rest of the body and fins of this fish are completely transparent with an iridescent sheen visible in bright sunlight. But it is almost impossible to see the fish already at a shallow depth.
The hardest part of the body is the head with strong jaws and strong piercing teeth. The thin diamond glassfish feeds on small crustaceans, catching them one by one and chewing. This fish digests small crustaceans entirely, and regurgitates the shell after digesting soft tissues when swallows large ones.
This fish species has large silvery eyes and a double lateral line. Usually, fishes of this species drift in congestions of plankton with the current and make only short rushes for prey.
Sexual maturity comes at the age of 1 year, with a length of about half of the maximum size. Fishes spawn in a school of relatives, simply spawning eggs in the water column and not taking a parental care for the offspring. There are up to 10 million eggs in the clutch; spawning repeats 4-5 times during the year. Fry feed on plankton, and also absorbs organic substances from the water with the entire body surface. Life expectancy is no more than 6 years.
Spotted diamond glassfish (Platyrhombus maculatus) inhabits the temperate waters of the southern hemisphere. It is a fish up to 60 cm long with a relatively large head, feeding on small cephalopods and pelagic worms. This species also has a translucent body with some black spots in the upper half of the body. Its biology is similar to that of the previous species, but it differs in faster growth: it reaches puberty at the age of six months and lives no more than 4 years.
In the southern part of the Atlantic Ocean, false-eyed diamond glassfish (Platyrhombus oculifer) lives; it is a fish up to 90-100 cm long, differing from most species of the genus in coloration features. Its color is silvery with a prominent shine, and in the anterior third of the body behind the head, there is a pair of large ocular spots of black color with a yellowish luster. These fake eyes create the impression of a large dangerous fish and protect the false-eyed diamond glassfish from predators. This species feeds on large coelenterates and pelagic gastropods and spawns seasonally, yielding 2 clutches of up to 4 million eggs during the summer.

Crystal leaffish (Leptocephalomorphus phylliformis)
Order: Tarpons (Elopiformes)
Family: False leptocephali (Pseudoleptocephalidae)
Habitat: coastal waters of South and Southeast Asia, mangrove forests and estuaries.
In the course of the evolution of the Elopiformes order, a group of fishes emerged, that kept in adulthood the features of leptocephalus – the larval form of their ancestor. This course of evolution turned out to be very successful: many species inhabiting the open ocean appeared among these fishes. They belong to the Pseudoleptocephalidae family and to some related families. Most of these fish inhabit the open ocean, but there are species adapted to life near the shores, as well as in the estuaries with water of lowered salinity. Some species are even able to live in fresh water for a long time, but they always reproduce in the sea.
One of the coastal species of pseudoleptocephalids is the crystal leaffish, a small fish species inhabiting the coastal areas of the Indian Ocean. This delicate-looking fish reaches 15-20 cm in length. Its body is almost completely transparent, except for the silver lining of the peritoneum and skull. The body shape of this fish is similar to the greatly enlarged leptocephalus of eels known in the human epoch: the body is strongly laterally compressed and deep, oval in shape with a pointed head and tail. The head is relatively larger than that of leptocephalians, with large silvery eyes, well-developed jaws and pointed teeth. The unpaired fins are narrow; the dorsal fin stretches from the head to the caudal fin, the anal fin – from the middle of the length of this fish. The tail-stem is deep; the caudal fin is fan-shaped and does not fuse with the dorsal and anal fins. The pectoral fins are greatly reduced. The lateral line forms three branches of sensitive cells on each side.
Despite its seeming fragility, this species is a very hardy fish, perfectly adapted to life in the changeable conditions of estuaries. The musculature is well developed and allows the fish to move against the current and resist the surf. Crystal leaffish endures both sea and almost fresh water. It is a schooling zoophagous fish species; its schools number up to several hundred individuals.
The basis of the crystal leaffish’s diet is made of small crustaceans and worms. In almost fresh water, these fishes feed on insect larvae and small fish fry.
Spawning of this species is in schools and takes place exclusively in seawater of normal salinity. A school of fishes is preparing to breed almost simultaneously due to the exchange of chemical signals between individuals. Each female spawns about 50 thousand small eggs at once. Floating eggs are spawned into the water and carried away to the sea, where further development takes place. During the year, spawning is repeated 4-5 times. Small transparent fry live in plankton for up to 2 months, then move closer to the shore and settle in estuaries. Schools usually form of individuals of the same age and size.
Sexual maturity takes place at the age of 6 months; life expectancy is up to 5 years.
In the rivers of Hindustan, a related species lives – punctated leaffish (Leptocephalomorphus punctatus). This fish reaches 13-15 cm in length and spends a significant part of its life in fresh water. In body shape, this species is similar to the previous one, but differs in the presence of numerous black dots on the covers of its transparent body. These dots are rarely scattered across the front part of the body, but are more numerous on the tail. This species is a predator and eats worms, crustaceans and small insect larvae. For reproduction, fishes gather in numerous schools and migrate to the sea shallow waters. Fertility is over 80 thousand eggs, but spawning repeats only twice a year. Life expectancy is no more than 4 years.

Vumurt (Deinoesox vumurt)
Order: Pikes (Esociformes)
Family: Pikes (Esocidae)
Habitat: Fourseas, the central part of the reservoir away from the shores.
Pike (Esox lucius) turned out to be one of the most successful fish species of the human era. Despite fishing and habitat destruction, this species survived the human era and changes in the biosphere at the turn of the Holocene and Neocene. Vumurt is one of the many descendants of the pike that inhabits the Fourseas and leads a pelagic lifestyle. The name of the fish is the name of the water from the Udmut legends. Like the Baikal pelagic pike (Pelagoesox sphyraenoides), it is a large solitary predator attacking solitary fish. Vumurt is very cautious and fast, because it is not easy to get close to prey in open water. It is one of the dominant predators in areas of the Fourseas remote from the coast, and its only enemy is the tsar-fish (Pseudohuso cataphractus), from which the vumurt escapes only due to its speed and maneuverability.
With its appearance, vumurt resembles a pike. The body length of an adult fish is up to 2.2 m, the weight is about 55 kg. The fish has a very muscular body of streamlined shape, a long head and a deep crescent-shaped caudal fin. In the dorsal and anal fins, the anterior rays are very rigid and thickened, allowing it to keep the fins open during the movement. The general coloration is silver–blue with indistinct vertical stripes on the sides. This fish species is an active predator. There is a distinct specialization in the structure of teeth: the lower jaw has a pair of collapsible teeth that cause serious wounds to the prey, from which even relatively large fishes die. The bases of these teeth are placed in sacs formed of soft tissues. At rest, the “hunting” teeth lay down inside the mouth, with their tips backwards. At the base of each such tooth there are several replacement teeth of varying degrees of development. When a tooth falls out, it is quickly replaced by a new one. Vumurt feeds on medium-sized prey – from gobies to juveniles of local sturgeons. Sometimes this fish can swallow lone boneside (Nanacipenser osteopleurus) entirely, but only the largest individuals are capable of this.
During the hunt, vumurt carefully approaches the prey and makes the final rush. At the moment of capturing prey, the teeth in the lower jaw erect and stick into the soft tissues of the prey. Fishes that have escaped from the teeth of vumurt often die from wounds or bear scars. Sometimes young seabirds and ducks and geese resting on the water during their migrations fall prey of vumurt. Vumurt attacks flocks of low-flying birds, jumping out of the water to a height of up to 3 meters, and drags prey into the depths.
Spawning at vumurt takes place in late March-early April. At this time, fishes begin gathering in coastal areas with fresh water, often near the mouths of rivers flowing into the Fourseas. At this time, the appearance and behavior of fish change greatly. The courtship dress is strikingly different from the usual one: the background color of the body is reddish, and there are about 20 black arc-shaped stripes on the sides, directed towards the top of the head. The fish's head is black at this time. Males and females “hover” in front of each other in the water with their heads up, synchronously moving their fins. Pairs of fish stay near the surface of the water, sometimes sticking out the tips of their jaws into the air. When an opponent tries to court the same female, fights take place between males: they snap their teeth, drive a wave at each other with their tails and ram each other with their heads. During intraspecific conflicts, “hunting” teeth are not used. The excitement of the fishes soon reaches its apex, and they begin to react violently to external stimuli: a bird flying over the water makes them jump out vertically, although they make no attempts to snatch it. During the climax of spawning, the male strongly presses against the female, forcing her to sink to the bottom. At this time, the female spawns eggs – in the clutch of a normally developed adult, there are up to 200-250 thousand eggs glued together with strongly swelling mucus. Lumps of vumurt eggs lie on the bottom and on underwater plants; adult fishes do not guard the clutch and leave coastal areas immediately after spawning. After a couple of weeks, the fry hatch out, which at first hide in the thickets. Up to a year-old age, young fishes feed on worms and scuds, then switch to fish fry. From this age, they can already eat their congeners also. By the end of the second year of life, young vumurts are increasingly moving away from the shore, hunting at depth, and adults already pass to completely pelagic life. These fishes reach sexual maturity at the age of 4 years, but they actively grow up to seven years old. Usually adults live up to 25 years, but occasionally there are older specimens.
A smaller Three-Rivers-Land vumurt (Deinoesox paravumurt) lives in the Three-Rivers-Land. It has a darker color with a greenish tinge and habits more like its ancestor; the length of an adult is up to 140 cm. This fish also displays a penchant for a pelagic lifestyle: it prefers deep waters and uses floating objects as a shelter to get close to its prey. This fish occasionally enters the coastal zone of the Fourseas and moves from one river to another; this is how the unity of the species is maintained.

This fish species was discovered by Nick, the forum member.

Fourseas needletooth (Subtilesox fragilis)
Order: Pikes (Esociformes)
Family: Pikes (Esocidae)
Habitat: Fourseas, near-surface layers of water up to a depth of 50 m.
In the age of man, Eurasian pikes (Esox lucius) managed to survive due to their unpretentiousness and ability to reproduce quickly. These fishes successfully existed in reservoirs slightly changed by people, and their populations were numerous enough to ensure the survival of the species as a whole. In the early Neocene, the area of pike in Eurasia was restored, and this species began to develop the Fourseas in due course of the decrease of water salinity and the expansion of this reservoir. By the time the salinity of the water dropped to an acceptable level for pike, a community of planktonic organisms had formed in the central part of the Fourseas. One of the descendants of the pike moved into the water column and turned into the main planktonic predator – it is the Fourseas needletooth.
The appearance of Fourseas needletooth has changed a lot compared to its ancestor during the transition to a planktonic lifestyle. This species is a fish up to 35-40 cm long, although there are some individuals up to 50 cm long. It is a graceful pelagic predator with long and thin teeth, feeding on planktonic animals – crustaceans, insects and small fishes, usually gobies. The body of Fourseas needletooth is translucent, very narrow and ribbon-shaped. On the sides, separate small spots of green and brown color are scattered, forming a blurred cross-striped pattern. The internal organs are shielded by a silvery peritoneum. This species swims poorly and can only make sharp single rushes for prey. Usually, the Fourseas needletooth moves slowly in the water column, moving its dorsal and anal fins, and keeping its balance with the movements of the pectoral fins. Dorsal and anal fins are well-developed and wing-shaped, with muscular bases. The caudal fin is short.
The eyes of this fish are large, strongly convex, shielded from the outside with a silver lining. The head is about 40% of the total length of the fish and has turned to a tool for the consumption of planktonic animals. This fish has thin and flexible jaw bones connected by elastic webbed soft tissues, and gills with thick gill rakers that allow small prey to be trapped in the mouth cavity. The teeth are very numerous, but thin, up to 20 mm long. They stick out when jaws are closed, and with half-closed jaws they form a kind of thick sieve. Having captured a portion of water with planktonic animals with its mouth, the Fourseas needletooth releases water through its gills and through its teeth. The main food of this fish includes planktonic crustaceans, insects and pelagic fry of local fish. These fishes are relatively tolerant of their congeners, but prefer to keep a distance. If two fish meet, they stand parallel to each other and exchange body movements, launching waves on each other and evaluating the opponent by their strength.
In winter, the Fourseas needletoothes become much more tolerant of each other. Fishes go deep and gather in small schools, slowly moving in the water column. At this time, the gill rakers partially degrade and fishes do not feed, preserving energy reserves for spawning.
In the spring, fishes move into the upper layer of water and arrange courtship games. Males begin to call females, gathering in schools, making series of clicks and opening their mouths wide. The female, accepting the courtship of the male, swims parallel to his side, and both fish leave the congestion of males. The female spawns up to 200 thousand small transparent eggs into the water, which are immediately fertilized by the male. Fishes do not take care of eggs, and a significant part of the offspring die in the first weeks of life. The young begin to feed on planktonic crustaceans and for some time are grabbing predators. With the growth of teeth and an increase in the length of the jaws, it gradually switches to feeding on plankton, and from a length of about 5 cm, young fishes feed exclusively on plankton.
Sexual maturity comes in the second year of life with a length of about 15 cm . Life expectancy usually does not exceed 5 years.

Spotted paradise pike (Leptoesox multicolor)
Order: Pikes (Esociformes)
Family: Pikes (Esocidae)
Habitat: rivers of the Japan Archipelago – lower and middle reaches of the rivers in the north and northwest of Honshu Island.
In the human era, salmonid fish were characteristic representatives of the ichthyofauna of streams and fast-flowing rivers – mainly a variety of trout that originated independently from various diadromous salmon species of Eurasia and North America. In the human era, their numbers and diversity have greatly decreased due to fishing, pollution and habitat destruction. In the Neocene, salmoniform fishes became extremely rare, and their place in the Holarctic ecosystems was taken by fishes of other groups. In the conditions of island isolation in the rivers of the Japan Islands, peculiar ecological “substitutes” of trout evolved in the Neocene – small insect-eating pikes of variegated color, forming a separate genus of paradise pikes.
The appearance of these fishes is quite recognizable: they resemble pikes of the genus Esox, but differ from them in a very graceful physique. The thin body of this fish reaches a maximum length of 30-40 cm, but is often smaller. These fishes have narrow heads with long snouts; the mouth is able to open very wide. A characteristic feature of the development of the dental system is the difference in the size of the teeth: the teeth in the front of the jaws are strongly developed and protrude from the mouth even with the mouth closed, and in the back of the jaws, they are small. This is due to the peculiarities of the diet: fishes often hunt flying insects, snapping them while jumping out of the water.
Paradise pikes inhabit fast-flowing streams and rivers, so they have to constantly live in conditions of strong currents. They swim well and can withstand the current for a long time, as well as make jumps up to 1 meter high while hunting for insects. The caudal fin of these fish is two-lobed, the tail-stem is strong and muscular; the fins are shifted to the rear of the body. The anterior rays of the dorsal and anal fins are rigid.
Vision plays an important role in the life of paradise pikes. The eyes of these fish are large, shifted to the upper part of the head. Fishes hunt down insects and attack them, taking into account the peculiarities of the refraction of light when passing from air to water. Also, fishes distinguish relatives with the help of vision. The body coloration of the paradise pikes is often spotted or striped, or has distinctive spots. The rivers of the Japan Islands are inhabited by several species of paradise pikes forming a large number of local forms differing in color.
Spotted paradise pike is a typical representative of the genus. This is a fish up to 40 cm long, of gracile constitution. The background color of the body is emerald green with a darker back; the sides are covered with numerous white spots. The fins are orange in color, transparent at the edges. Male and female do not differ in color; the female is only slightly larger than the male.
Paradise pikes are solitary fishes that prefer to live in fast flowing water. Each individual has its own territory, including both banks in a narrow stream, and a section of one of the banks in wider rivers. Usually fishes prefer to keep their heads against the current, near some shelter – a stone or a snag. In case of danger, the fish quickly hides in the shelter.
Paradise pikes feed mainly on insects. They catch insects that have fallen into the water, hunt water beetles and dragonfly nymphs in the water column and at the bottom, but in summer, they most often attack flying insects by jumping into the air. Dragonflies and mayflies, butterflies and beetles become their food.
The spawning of spotted paradise pike takes place in the spring. At this time, fishes begin to be more tolerant of each other and form breeding pairs. The formed pair of fishes keeps near a large bush of aquatic plants and together performs a “courtship song” of rhythmic clicks and tapping. Fertility is up to 50 thousand small eggs. These fishes are pelagophiles: the eggs are immediately carried away by the current and develop in the lower reaches of the river, sinking between rocks or among thickets of aquatic plants. Young fishes also live in the middle reaches of rivers, feeding on planktonic crustaceans and juveniles of other fish species. As they mature, young fishes gradually rise upstream; during the journey, they easily jump over river rapids and waterfalls up to 1 meter high. Sexual maturity comes at the age of 2 years, and life expectancy rarely exceeds 20 years.
Other species of paradise pikes live in the rivers of Japan Islands:
Black-backed paradise pike (Leptoesox melanodorsa) inhabits the rivers of Hokkaido Island and the mountainous areas of Honshu Island. This species has bright green sides with small white specks; a black longitudinal stripe stretches from the snout to the tail along the back. The fins are transparent; there is a small black area at the base of the dorsal fin. In some local forms, white mottling prevails over the background color; there are also forms with a very thin black stripe on the back.
Four-eyed paradise pike (Leptoesox tetraoculata) is the rarest species: it inhabits only the shallow lower reaches of rivers in the southern part of Honshu Island. It has a dull green body color, a pale gray belly and orange fins. There is a large ocular spot on the base of the tail fin – black one with a thin white border. This spot is a protection against birds of prey, disorienting them. Unlike other species, intraspecific variability is weakly expressed.
Decorated paradise pike (Leptoesox ornata) lives in streams and mountain rivers of Shikoku Island. This species has a bright color of unpaired fins – they are red with an orange border. The body color is very dark – the sides are brownish-green, the back is black, the belly is yellowish-white; there is a white speck on the back half of the body. In some forms, the color is much lighter, but the red color of the fins is almost always preserved. This species feeds mainly on small fish and aquatic insect larvae.
Dwarf paradise pike (Leptoesox minima) is the smallest species of the genus: the body length of an adult is no more than 25 cm. Unlike other species, it has a sandy-golden color with gray spots on the back and transparent fins. It is a benthic species found in the lower reaches of rivers along the coast of Kyushu Island in areas with sandy bottoms and sparse thickets of marsh plants. In the mountainous areas of the island, there are local forms of this species, characterized by a darker color; the gray speckles spread to their sides and belly, and the background color becomes ochre-red.

Trollgaddor, troll pike (Trollgaddorus esocidus)
Order: Pikes (Esociformes)
Family: Pikes (Esocidae)
Habitat: rivers and lakes of northern Europe.
Appearing back in the time of the dinosaurs, in the Cretaceous period, pikes were a small, but quite tenacious family of bony ray-finned fishes. They could survive even in peat ponds and lakes, forming a rather peculiar food pyramid there, based on cannibalism at all its levels – and it was one of the features that helped them survive the ice age at the turn of the Holocene and Neocene. Many other species of animals were driven to the south, and returned to the north much later, but some pike populations remained in the north at that time, and survived the ice age there.
Of course, most often, pikes devoured not each other, but other living creatures, and in farther southern latitudes they occupy niches of the top predators of ecosystems – many species of Neocene pikes live in the Fourseas, in Baikal, etc. But one of the larger species, the troll pike, lives precisely in the north.
The troll pike or trollgaddor (named after a creature from Scandinavian mythology) is a very large species. Like some other cold-blooded animals, the troll pike grows all its life, and especially old individuals can exceed 2.5 m in length with an appropriate weight – up to 40-50 kg. Like most other pikes, troll pike has a rather slender body: for such a large fish, it has a slim build, which does not affect its appetite at all.
Like most other pikes, the troll pike hunts from ambush; this fish has a green color with darker vertical stripes, which makes the troll pike hardly noticeable in its native environment; with age, the troll pike gets a monotonous dark color, which together with its body shape makes it look like a piece of sunken wood.
Trollgaddor is an almost omnivorous predator: fishes are equally willing to eat fish, amphibians, reptiles, aquatic and near–aquatic birds and animals. Troll pike hunts from ambush: it waits for the prey to approach it, after which a rush is made, and pointed teeth cling to the prey. Having snapped its prey, the trollgaddor shakes it with lateral movements of the head, inflicting additional wounds on it until it dies; the troll pike tears large prey into pieces in this way, and it simply swallows small ones whole and alive.
The spawning of troll pikes takes place in early spring, when ice is still floating on the surface of the water. Females begin to search for places convenient for spawning eggs – usually in last year’s remnants of thickets of underwater plants. Males search for females by the sounds they utter, and sometimes several males gather around one female. Each male also manages to participate in courtship rituals with some other females several times. Fertilization of eggs takes place without complicated ceremonies; the mating group of fishes betrays its presence by splashing when males cling to the female’s body. The clutches are large: there are 200 or more thousands of fairly large eggs. They are sticky and stick not only to underwater plants, but also to the feet of waterfowl that carry them to new reservoirs; these fishes lack parental instincts, and an adult trollgaddor may well eat a smaller one if it is too careless.
The growth of this species is long and slow; sexual maturity of the troll pike does not come earlier than at the age of 7-10 years, and if this fish grows to at least one and a half meters long, it will be able to live for several decades and even more.

This fish species was discovered by Bhut, the forum member.

Grass pikelet (Microesox microesox)
Order: Pikes (Esociformes)
Family: Pikes (Esocidae)
Habitat: central and eastern Europe, oxbows and overgrown areas of rivers.

Picture by Lyagushka based on the picture by Kazimir Adamovich

Northern pike (Esox lucius), which lived in the age of man, had a wide range and was a rather unpretentious species. It successfully coexisted with humans, survived the ecological crisis, and in the Neocene on Earth there are numerous descendants of this species occupying various ecological niches. One of them is the grass pikelet, a medium–sized fish reaching a maximum length of about 40 cm and a weight of about one kilogram. Its physique resembles the redfin pickerel (Esox americanus) known in the human era.
The body of the fish has a greenish color with transverse brown veinlets – this is an excellent camouflage in dense coastal thickets. It has relatively large eyes and a narrow snout with thin teeth curved back. By its feeding type, it is an ambush predator feeding on small fish, including its own young, as well as aquatic insects and their larvae.
Spawning in this species takes place in late spring, when aquatic vegetation is already growing after winter. Spawning takes place in pairs, accompanied by chasing partners after each other and jumping out of the water. The female is larger and slightly paler than the male; fertility is up to 50 thousand eggs. Fishes do not guard their eggs. Young fishes feed on invertebrates and fry of other fish species. At the age of 2 years with a length of about 20 cm, young fish become able to reproduce. Life expectancy is no more than 15-20 years.
Grass pikelet prefers reservoirs with slow current and rich aquatic vegetation, and another species of this genus, silverish pikelet (Microesox argenteus), prefers small rivers and streams with swift current. This fish lives in the lower reaches of the mountain rivers of Central Europe and the Balkans, and differs from its relative in even smaller size and silvery body color with a dark back and an almost white belly. It has large eyes and relatively thin jaws with pointed teeth. In addition to small fish, this species willingly catches insects flying over the water and falling into it, often making high jumps out of the water. It usually stays in more or less calm areas of the reservoir near the surface, and spawns in quiet backwaters, spawning its eggs on aquatic plants.

This fish species was discovered by Kazimir Adamovich, the forum member.

Great wa'awa (Waawa pelagica)
Order: Milkfishes (Gonorhynchiformes)
Family: Milkfishes (Chanidae)
Habitat: Pacific and Atlantic Oceans, tropical and subtropical waters.
In the age of man, the ancient milkfish family was represented by a single species – Chanos, or milkfish (Chanos chanos). Human activity has significantly increased the chances of survival of this fish, since milkfish became a commercial fish and was settled in almost all tropical seas as an object of fish farming. Its survival during the “plankton catastrophe” at the turn of Holocene and Neocene was favored by its ability to live in coastal waters of lower salinity and unpretentiousness in the choice of habitats. In addition, this species was on one of the lower levels of the food pyramid because it fed by filtering microscopic algae from the water. Therefore, the populations of Chanos persisted in a few “shelters” in coastal waters, and in the early Neocene, their descendants began to populate the open ocean.
Due to low competition in the newly formed pelagic habitats of the early Neocene, the descendants of Chanos managed to gain a foothold successfully in these places for a long time, occupying an ecological niche of a consumer of phyto- and small zooplankton. A typical representative of the pelagic descendants of Chanos is great wa’awa (the name comes from the name of the ancestral species in the Mariana Islands). Thanks to the abundance of this food, great wa’awa has grown to gigantic size: the body length of an adult is about 4 meters. The body of this species is drop-shaped with a strong tail stalk compressed from the sides, silver-gray with a bluish metallic luster; the back is dark. Dorsal fin is rigid and elongated. Right under its base, there are strong elongated pelvic fins. The anal fin of this species is small and short – this is due to an increase in the mobility of the tail stalk, on which sides powerful tail keels are developed. The fish is adapted to long-term swimming at high speed in search of suitable feeding areas. Tail fin of this species is deep, rigid and crescent. The color of the fins is light gray. Pectoral fins are elongated and pointed, serving as elevators during its movement.
Great wa’awa feeds mainly on small phyto- and zooplankton. The large head of this fish has a wide mouth (the corner of the mouth is far behind the vertical of the posterior edge of the eye) and a highly developed gill department. The mouth of great wa’awa opens very wide, forming something like a pipe that takes up plankton from the water passively. The gill rakers form a filter apparatus that entraps even a mass of microscopic algae. During feeding, fishes of this species swim slowly in the upper layers of the water; from time to time, the tips of their dorsal and tail fins appear from under water. Great wa’awa forms schools of up to 200-300 individuals of the same age.
This species goes through its entire life cycle in pelagic habitats, away from the coast. The spawning of great wa’awa is portioned; there is no specific breeding season. Due to chemical signals, the next portion of eggs ripens in adult fishes almost simultaneously. The single fecundity of the female of the great wa’awa is up to 20 million small eggs. Spawning occurs quickly and violently, accompanied by vertical jumps of fishes to a height of up to 3-4 meters. Like all pelagic species, great wa’awa does not care about offspring. This species has pelagic eggs developing in plankton for up to 5 days. Larvae spend up to 2 months in plankton, after which they undergo metamorphosis and gather in schools. In the first year of life, the young fish reaches a length of about 20 cm. Sexual maturity comes at the age of 5-6 years, with a body length of about 2 meters, after which the growth rate decreases significantly. Life expectancy reaches 50 years.
The tropical waters of Indo-Pacific are inhabited by a close species, green wa'awa (Waawa viridescens) – a fish 2-2.5 m long. This species prefers coastal habitats and stays above depths not exceeding 200-300 meters. The coloration of this species is characterized by a distinct greenish metallic sheen. Green wa’awa feeds mainly on phytoplankton and often stays near the mouths of rivers that carry nutrients into the ocean that contribute to the development of phyto plankton.

Southern crystal catfish (Crystallameirus pseudosatan)
Order: Catfishes (Siluriformes)
Family: North American freshwater catfishes (Ictaluridae)
Habitat: cave reservoirs of the South Island of New Zealand.
A characteristic feature of the geography of Neocene New Zealand, as in the age of man, is a presence of extensive cave systems, often filled with water. They harbor a sparse but peculiar fauna consisting mainly of various invertebrate species. The vertebrates of the caves are represented by two amphibian species – the cave frog and the cave false salamander. Their neighbor is a very small fish species – southern crystal catfish.
This fish is a distant descendant of the brown bullhead (Ameiurus nebulosus) introduced to New Zealand by people. Compared to its ancestor, the crystal catfish seems to be a true dwarf – its maximum length is 5 cm, of which the head accounts only 1 cm. Such small size is associated with the poverty of ecosystems of underground reservoirs. The appearance of the crystal catfish is typical for cavefishes: its translucent body lacks pigment and has a pale pink color. The eyes are completely reduced, only in young fishes dark spots shine through in their place. For spatial orientation, this fish uses well-developed senses of smell and touch. In this regard, there are wattles on its lower jaw and in the corners of its mouth, the length of which exceeds the length of the head: 4 wattles on the lower jaw, 2 in the corners of the mouth. The lateral line is also well developed.
The main food of southern crystal catfish includes small invertebrates. In addition, it eats carrion, scrapes bacterial and fungal films from the walls of caves with its thick lips and steals the eggs of local amphibians. Cannibalism is a common phenomenon among these fishes. In addition to their larger relatives, false salamanders pose a danger to crystal catfish. The metabolic rate of the crystal catfish is very low, which allows it to be content with a small amount of food and starve for a long time.
The change of seasons is not pronounced in the caves, so the crystal catfish does not show seasonality in mating behavior. The female can lay eggs up to 3 times a year, but the clutch size is small – only about 50 eggs. The female’s readiness to reproduce depends on its physical condition. The male finds a female ready to spawn and begins to court it, touching her with his wattles and swimming around her. A recess or crack in the cave wall or between the stones at the bottom is chosen as a place for the clutch. Males of this sish species have a highly developed parental behavior: during the entire incubation period, the father does not leave the eggs and selflessly protects them, attacking any living creature that approaches them. At the same time, it almost does not feed, eating only invertebrates that are in the immediate vicinity of the clutch. Incubation lasts for several weeks. After its completion, the fry stay in a group for about a day near the place of clutch, and then swim away. There are reasons for this: after their hatching, the male gradually loses interest in the fry and can easily eat them.
The lifespan of a crystal catfish can reach 10 years.
A close species, the northern crystal catfish (Crystallameiurus pygmaeus), lives at the North Island of New Zealand. The separation of the two species had taken place in the early Neocene, when the Cook Strait again separated the Northern and Southern Islands of the archipelago, which were connected to each other during the ice age. The northern species differs in body proportions (the head is larger and the body is more elongated) and lesser number of rays in the caudal fin. Despite the slight external differences, these species are very different genetically.

This fish species was discovered by Simon, the forum member.

European toad-faced catfish (Coryurus coryurus)
Order: Catfishes (Siluriformes)
Family: North American freshwater catfishes (Ictaluridae)
Habitats: Europe – rivers, streams, streams.

Down from the top: normal, melanistic and albino coloration

Picture by Lyagushka

In the human era, many species had been settled far beyond the borders of their natural ranges. After the human disappearance and changes in the biosphere at the turn of the Holocene and Neocene, they survived, and their descendants are widely represented in the Neocene fauna. The brown bullhead (Amiurus nebulosus) was introduced to Europe from the reservoirs of North America. Initially, people tried to breed it as an object of aquaculture, but in vain: this catfish degenerated into a stunted low-value fish, and later began to populate European reservoirs independently – already as a pest species, and very unpretentious and tenacious. One of its Neocene descendants is the European toad-faced catfish. It differs in lifestyle from its ancestor: it is a small schooling fish living at the bottom of rivers and streams. In part, it is an analogue of corydoras catfishes (Corydoras) from the reservoirs of South America.
This species grows up to 15 cm in length (males are smaller). It has scaleless skin; for protection from predators, pointed hard spikes in the dorsal and pectoral fins are preserved – their prick is very painful. The body has a dirty gray background color with black mottling on the sides, a dark back and a white belly. Occasionally, albinos and completely black individuals are found in populations. The fish has a flat head with a wide mouth surrounded by eight wattles – two long ones at the corners of the mouth, two short ones on the upper jaw, and four ones on the lower jaw. The eyes are small, yellow and shining in the dark.
This catfish lives in overgrown reservoirs and keeps to the edge of thickets of underwater vegetation. It feeds on benthic invertebrates, carrion and eggs of other fishes. These fishes are the main reason for the decline in the number of juveniles of cyprinids and other fishes.
In this species, fertility reaches only 250-300 eggs, but the survival rate of the offspring is very high. This catfish spawns in burrows dug by males, often forming
“rookeries” of dozens of burrows on the area of several square meters. Spawning occurs in early summer, when the water warms up well. Males attract females with sounds resembling gnashing and croaking, producing them by rubbing bones against the swim bladder. The incubating male covers the entrance to the burrow with its head, and drives unwanted guests away with short sharp blows of his head. Large fish can be attacked by several males at once.
Incubation lasts about a week, after which the male leaves the burrow, but bears offspring in his mouth for several more days. Young fishes hide in the thickets of plants, in autumn they form schools of the same age. During wintering, fishes hide at the bottom of the pools in numerous schools and secrete a large amount of slime, which prevents the predator from snapping them. Sexual maturity comes at the age of 2-3 years, life expectancy is up to 20 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

North Island River Catfish (Megalourus novazealandiae)
Order: Catfish (Siluriformes)
Family: North American freshwater catfishes (Ictaluridae)
Habitat: rivers and lakes of the North Island, New Zealand.
New Zealand was distinguished in the Holocene by a freshwater fish fauna consisting mostly of descendants of saltwater species, but this changed during human occupation. In the Holocene man brought various invasive fish for sport, carp, trout and Brown Bullhead Catfish (Ameiurus nebulosus), all of which have left descendants in the Neocene.
Descendants of Brown Bullhead include predatory catfish of large size, analogs of large tropical catfish of South America; this is the North Island River Catfish. It is one of the largest predatory fish in the fresh waters of New Zealand, reaching up to 1.5 meters long and 65 kilograms in weight, being a carnivore which feeds on insects, clams, crustaceans, fish, small and mid-sized vertebrates such as frogs, rodents and birds. Coloration is a greyish, with thick stripes of dark brown and small spots, belly is dirty white. Body shape generally resembles its ancestor, but tail fin is more triangular in shape. Head is broad and flat, as with most catfish, mouth wide and upturned with a protruding jaw, barbells are long and backswept.
This fish is less generalized than its ancestor, and is not as tolerant of poor water quality. It is active mainly during twilight and night-time. Behavior is generally solitary, and males will chase away interlopers on their territory.
Spawning generally occurs during summer rains, from December to early February, when water is high level and warm in temperature. Females are monogamous, only mating with one male per season; males seek out females by scent. Overtures to the female involve soft biting and grabbing, as well as swimming side by side. The female lays her eggs in a nest in a sheltered spot such as a snag or hollow log, and these are fertilized by the male as they are laid. Both male and female protect the eggs until they have hatched, which can take up to two weeks. Both parents will care for the fry for up to a week after hatching. Egg clusters can contain up to 3000 eggs, fish reach sexual maturity at about 3 years old. Life expectancy can be up to 30 years.

This species of fish was discovered by Timothy Morris, Adelaide, Australia.

Humpback sea catfish (Gibbosciades gastrogravidus)
Order: Catfishes (Siluriformes)
Family: Ariid catfishes (Ariidae)
Habitat: Central America, Caribbean Sea, Gulf of Mexico, Mississippi Delta.
In the age of man, catfishes have lost a relatively small part of their former diversity. Mainly, species from rivers of tropical rainforests have suffered because of human activity. At the family level, the losses of catfishes were minimal. Among marine siluriforms, mainly large species that were the object of local fishing suffered from overfishing, while the number of small species remained at the same level. At the turn of Holocene and Neocene, the boundaries of the habitats of a number of sea-dwelling catfishes shifted to equatorial latitudes, which led to increased competition and extinction of a number of species, but after the end of the ice age, the survived species began to settle to new habitats, evolving actively and developing peculiar survival strategies.
The coastal waters of Central and North America north of the Panama Strait are inhabited by the humpback sea catfish, one of the largest species of marine ariid catfishes. The ancestor of this species is a certain species of euryhaline catfish of the genus Sciades widespread in the tropical waters of the New World in the human era. Its descendant has become a relatively large creature: the length of an adult reaches 150 cm, and occasionally individuals up to 2 meters long appear. This species inherited from its ancestors tolerance to changes in salinity of water; it inhabits coastal waters, is often found in brackish water and enters the lower reaches of rivers. Unlike related species, it is a solitary fish species that stays at the bottom and does not swim in the water column.
This fish differs from its relatives by a specific well-recognized body shape. The head of individuals of both sexes is wide and flattened; small eyes are located behind and slightly above the corners of the mouth. Behind the head, the body rises steeply up to the base of the dorsal fin. The upper part of the head and the back up to the dorsal fin are covered with shell plates. A ready-to-breed male develops a large fat hump on his back behind the dorsal fin, showing his good physical condition. In well-fed fish, the base of the adipose fin is “sunk” into the hump. The fins are pointed; strong poisonous spikes grow at the front edges the dorsal and pectoral fins. Tail fin is two-lobed, with a deep cut at the posterior edge. 3 pairs of wattles grow on the head of humpback sea catfish: 1 pair of long wattles on the upper jaw and 2 pairs of short ones on the lower jaw.
The body color of this species represents a camouflage pattern: dark back, brown sides with a lighter “marble” pattern and a grayish-white belly. The fins are dark grey.
Humpback sea catfish is a predator and feeds on any prey that it is able to swallow: crustaceans, small fish and cephalopods. In river deltas, these catfishes feed on waterfowl and shorebirds. Hunting them, the catfish quickly rises from the bottom, turns upside down and captures prey from below. An adult one easily swallows a small duck whole.
This fish species is remarkable for its way of caring for offspring: it bears eggs in its stomach. It is performed exclusively by the male, who is well fattened before spawning and accumulates a significant amount of fat in its hump. Courtship games in this species include the male displaying its fat reserves. The male swims above the female during spawning, turning one side to her, so that his silhouette stands out against the light background of the water surface to show how much his back is arched. At the same time, the male “sings”, uttering cracking and “quacking” with spikes of his pectoral fins.
Spawning takes place during the daytime on the area of the bottom, which the male and female clear together, while communicating with loud squeaking of their fin spikes. The female spawns up to 500 large eggs about 9-10 mm in diameter. The male fertilizes the eggs and then swallows them. By the time of spawning, he stops producing gastric juice, and his gastric mucosa thickens and becomes spongy: it swells and blood vessels grow into it. Once on the gastric mucosa, the eggs stick to it and quickly become overgrown with villi with blood vessels inside. Thus, the offspring of this catfish is supplied with food and oxygen through the circulatory system of the male. At the same time, unfertilized eggs and dead embryos dissolve gently, without damaging the normally developing eggs.
While bearing eggs, the male becomes very cautious. It hides among the roots of mangroves or in the thickets of underwater plants and does not eat anything, while consuming fat from the hump. After 3 weeks of fasting, young individuals about 3 cm long swim out of the stomach of an adult fish. The male takes care of them during the first week of life and hides them in his mouth if predators appear nearby. At this time, the expired epithelium with the egg shells peels off and is immediately digested. When the offspring leaves the male, he begins to eat normally, restoring its fat reserves. In the northern part of the range, spawning is seasonal and occurs in spring. In the southern part of the range, spawning can repeat twice a year.
Young fish feed on small aquatic animals and grow rapidly, reaching a length of 20 cm at the end of the first year of life. In the fourth year of life, they reach sexual maturity; life expectancy is up to 60 years.

Hornet catfish (Toxiglanis crabro)
Order: Catfishes (Siluriformes)
Family: Bagrid catfishes (Bagridae)
Habitat: Zinj Land, medium course of Indian Ocean basin rivers.
Zinj Land is huge subcontinent which broken away from Africa approximately 15 MY after the mankind extinction. It is separated from the basic continent with Tanganyica Passage which has passed just along the chain of Great African lakes. Salt water became an absolute obstacle for freshwater fishes, and species of Zinj Land began to evolve independently of African species. For 10 million years of isolation they had not formed any new family, but between Zinj Land and Africa there is no one common genus of freshwater fishes. Only representatives of migrating fishes may freely cross Tanganyica Passage and meet both in rivers of Africa and Zinj Land.
The rivers of Zinj Land are much shorter, rather than African ones, but conditions of life in them are more various: Zinj Land “had got” highest mountains of Africa. For freshwater fishes the communication between rivers of subcontinent flowing to the east (to Indian Ocean) and to the west (to Tanganyica Passage) is complicated, therefore in rivers of subcontinent the per cent of endemic fish species is rather high. But in any ecosystems struggle for survival is very sharp. Evolution process resulted in formation of diverse protective adaptations at fishes.
One of fishes living in rivers of eastern part of Zinj Land uses for self-defense poison – it is the reliable and repeatedly time-tested means. It belongs to bagrid catfishes for which sharp poisonous spikes in fins are characteristic. Poisonness and characteristic striped colouring have served as an occasion for the name: this fish is named hornet catfish. It is small fish (its length is about 12 – 15 cm) of contrast warning colouring. Out of spawning season these fishes have striped colouring – yellow with brown cross strips and white belly. Males differ from females in larger size and wider head.
At hornet catfish there is flat head with large shining eyes. On the top jaw of fish two long wattles in corners of mouth grow and two shorter ones stick up near nostrils. On the bottom jaw four short wattles grow. Fins of fish are pointed: it is preciously fast swimmer.
The hornet catfish differs in features of biology from many species of catfishes: it is diurnal fish hunting in schools in thickness of water to small fishes, tadpoles and water insects. At night hornet catfishes hide under floating leaves of water plants. At this time their colouring turns pale, and cross strips become narrow and faltering.
Poison is one of the basic means of protection at hornet catfishes. In back and pectoral fins of these fishes sharp spikes grow, in which basis advanced poisonous glands are located. Besides one more feature of this fish makes it similar to wasp: at this species the effective group protection is developed. Having noticed a predator, the fish of this species utters warning signal – it makes sharp scratching sound with the help of spikes of pectoral fins. At the alarm signal all fishes gather to spherical school (as at marine catfishes (Plotosus) of Holocene epoch). Angry fishes lift spikes, and their colouring becomes much more contrast. Hornet catfishes do not hide from the enemy – they entirely rely on efficiency of group demonstration. The sting of spikes of this catfish is dangerous to predatory fishes. The seized catfish spreads fins wide and sticks spikes in gullet walls of predator attacking him. The predatory fish can even die, having choked with such catfish. Therefore after attack on these catfishes predators had survived do not attack them any more.
When hornet catfishes are quiet, their school swims in river, having stretched to long rank. Fishes exchange sound signals and keep up movements of congeners, keeping a distance.
The spawning of these fishes takes place at night. After plentiful rains which serve as stimulus to spawning males of hornet catfishes gather to separate schools and “sing a chorus” involving females. Their colouring changes: in courtship dress male has black head and white lips, the body color stays like former one. Male ready to spawning shows to the female widely opened mouth, and thus with the help of pectoral fin spikes utters sounds similar to grasshopper chirring.
Demonstration of mouth till courtship display is not casual: it is connected to way of care of posterity at hornet catfish. Males bear eggs in mouth – such way of care of posterity appeared independently at fishes of various families and orders including catfishes of other families. Fertility of this species amounts about 100 large orange eggs incubated within one week. Males bearing eggs gather to dense school and keep in common: it helps them to protect against predators. Such school may total over hundred of fishes, and sometimes in one school it happens up to half thousand of males incubating eggs. At this time they have characteristic colouring – they are white with narrow vertical black strips on body and black top part of head. The forward part of back fin where the large poisonous spike is located gets reddish-brown color and is well appreciable from afar. When the predator comes nearer, fishes gather to spherical shoal and utter warning sounds in common. Loudness of alarm signal is proportional to the size of predator – all flight of fishes reacts to occurrence of large predator.
Helpless larvae hatch from eggs; they lay in mouth of the male motionlessly, yet yolk sac will resorb. At the fourth day of life when it occurs, larva turns to fry. First days of life fry have badly advanced spikes, but at this time they are reliably protected from enemies by care of the male. Fry distinguish the parent male by smell and keep nearby from it swimming out from its mouth. They start to feed, eating slime emitting on the body of the parent. About one week after larvae had turned to fry male hides them in mouth in case of danger (like fishes of cichlids (Cichlidae) family known to people acted). At this time schools of males with posterity move to shallows overgrown with plants where fry have an opportunity to feed on small animals.
Every day fry swim out of parental mouth for a longer time and depart from the male farther. Sooner or later they leave loving father absolutely and start to lead independent life. When the male will have no fry to keep, it starts to eat. For one year the male can bring up to three hatches of fry.
When fry become independent, at them spikes quickly develop, and young fishes become protected from predators. Passing to independent life, fry become cross-striped and group to schools. Schools may unite or broken depending on amount of forage. Main enemies of young hornet catfishes are larvae of water beetles and water bugs. They do not swallow small catfishes entirely, but exhaust avoiding poisonous spikes. But adult fishes have almost no enemies.

Wattle-walking catfish (Barbambulus verticalis)
Order: Catfishes (Siluriformes)
Family: Long-whiskered catfishes (Pimelodidae)
Habitat: tropical latitudes of South America, channels of Amazon and Hyppolithe rivers.

Picture by Amplion, colorization by Biolog

In Neocene expansion of Atlantic Ocean had caused break of isthmus of Panama and changes in geography of New World. South America is shifted a little bit farther to the south, and the southern extremity of continent is located in zone of seasonal climate with rather cold snowy winter. But the north of the continent is still in zone of equatorial and tropical climate, and the grandiose river systems carrying their waters to Atlantic are stretched here again. Meandering on plains, Amazon river changed its channel many times during the early Neocene. In 25 million years after extinction of mankind the part of former Amazon basin became the basin of Hippolythe – one of former inflows of Amazon.
Huge rivers joining the circuit of inflows and lakes represent the places of rough evolution of freshwater animals. Usually live beings inhabit the top layer of river waters, rich in oxygen and well lighted. Here it is always enough of food – on the surface of water floating plants grow, and the bottom is covered with thickets of rooting hydrophytes. In wide channels, far from riverbanks, in transparent water the microscopic algae expand, giving food to pelagic fishes of various sizes, down to giant boltergillers (Potamocetus spp.).
But life is present not only at the top layer of water. Bottom “floors” of deep river channels are inhabited by creatures eating rests from the table of inhabitants of top layers of water. They live in the world where the sunlight can not penetrate at all, and eat few things, that fall from above. Food chains are short here, and specialization concerns only the way of search of food, but not a kind of the food.
One inhabitant of deep river channels of Amazonia is a strange fish spending more than half of life, standing on head. It is a wattle-walking catfish, the representative of diverse group of fishes characteristic for South America. This fish has rather strange manner of movement – in rest it takes vertical position and stands on head. Eight wattles surrounding mouth of fish are rather elastic, with muscled mobile bases. Their length exceeds length of body of fish including tail fin. On skin of wattles there is a great amount of chemoreceptors, and branchings of lateral line stretch to them. The role of wattles in life of this catfish is great: fish prefers not to swim, but “to creep” on wattles, moving them like spider legs. However the scared fish takes horizontal position and swims away, waving by the whole body. This fish lives in channels of large rivers at the depth over 20 meters, but in rivers which water carries a plenty of suspension and is non-transparent, these fishes live even at five-meter depth. At night these fishes can move to smaller depth in searches of food, but disappear in depth at the dawn.
The length of body of this catfish does not exceed 30 cm from which the flattened head with wide mouth makes about a quarter. Wattles may reach the length of up to 40 cm. Due to the anatomy of jaw bones the mouth of this catfish can extend forward as a tube to the half of head length. The body has cylindrical shape slightly narrowed to tail fin. The swimming-bladder and fat liver give to the body of fish the density close to density of water, therefore wattle-walking catfish appears almost “weightless” under water and wattles easily maintain weight of body of fish. Back fin is strongly shifted forward and its basis is approximately at the same level as pectoral fins. Not disturbed fish is able to swim in vertical position, making wavy movements by back and pectoral fins simultaneously. The moving back forward is carried out due to wavy movements of anal fin which stretches at half of length of fish. Fatty fin is very small and blade-like. In back and pectoral fins there are strong poisonous prickles.
Among senses at wattle-walking catfish senses of smell and touch are most advanced. Wandering on wattles on oozy river bed, fish receives from receptors the complete information on nearby presence of various animals – predators and prey. Sight does not play any significant role for this fish; eyes of adult individuals are underdeveloped. They are capable to distinguish light from darkness and too bright light frightens this fish. Colouring of this catfish is monotonous pale yellow; fins are transparent.
Wattle-walking catfish feeds on benthic invertebrates – crustaceans and to a lesser degree on larvae of insects which are rarer in deep sites of the rivers. The fish feels their presence with the help of receptors developed on wattles. Having defined the location of prey, fish cautiously “flies up” above the bottom with the help of fin movements, attacks prey from above and catches it by single movement of mouth.
Spawning of wattle-walking catfish occurs in pairs. Male involves the female, uttering loud squeaky sounds with the bases of prickles in pectoral fins. This species does not have complex spawning ritual. Male and the female “get acquainted”, touching each other by tips of wattles. During the spawning fishes adjoin stomaches, also keeping vertical position. Female lays eggs on male’s belly and leaves him; spawning repeats up to two times per year. In clutch it may be up to one thousand small eggs. Male bears them about one week, not ceasing to eat. Fry at once leave him, and male does not care of the posterity any more. Fry has other way of life, rather than adult fishes. Young fishes swim in top layers of water and at this time can settle to new habitats. They are almost transparent, and their eyes are normally advanced. They swim in horizontal position, but can hover in thickness of water for a short while, taking vertical position and spreading wattles apart. If the crustacean or fry of other species of fishes touches wattles, they make short throw and catch prey. As young fishes grow, they “settle” on bottom and gradually migrate in deep sites of river channel, being guided mainly by change of light exposure. Fishes of this species become sexually mature at the age of 1 year at length of about 17 cm.

Electric synodontis (Synodontocephalus electrophorus)
Order: Catfishes (Siluriformes)
Family: Upside-down catfishes (Mochcidae)
Habitat: rivers of Central Africa.
Natural accident of the end of Holocene has affected mostly ecosystems of open ocean and large seas. Natural communities of rivers had not suffered almost, though the river ichthyofauna had lost only some species of large fishes, mainly predators. But when conditions were stabilized, and also climate gradually began to improve, new species of fishes have borrowed become empty ecological niches. One of the most original predators of rivers of Western Africa is electric synodontis.
It is very large fish - the length of body reaches one and half meters, and weight exceeds 20 kgs (females are a little bit larger than males). The body of the electric synodontis is flat: it is the bottom-dwelling fish, preferring to spend time in ambush, hiding among driftwood and water plants. Head is wide, with long wattles - length of wattles at the top jaw is up to 1 meter; on chin there are 4 feather-like barbs about 10 cm long. Eyes are small, shifted to sides of head. In wide mouth there is set of very small teeth - they do not allow to crack catch half-and-half (as at sharks), but help to keep it.
Fins of this fish are rather short and rounded. In back and pectoral fins ahead there are sharp poisonous spikes – the protection against large predators. Tail fin is wide and two-lobed: this fish is lazy swimmer, preferring to hunt from an ambush.
Smaller relatives of this river giant, catfishes of Synodontis genus differ in various coloring: spotty and striped, sometimes contrast bicolor. Electric synodontis during evolution had developed cryptic colouring of black and brown spots on grayish-green background. The bottom part of body of this catfish is yellowish-white.
The main hunting weapon of the electric synodontis is latent under skin. It is a layer of modified muscles, able to generate strong electric charge with which help fish stuns catch: smaller fishes and frogs. This fish also uses electric charges for protection against enemies: large predatory water turtles and lizards. In due time people had found at small African synodontis catfishes ability emit very weak electric charges. Obviously, one of numerous species of these catfishes during evolution had turned this ability for its own benefit, having strengthened power of electric batteries in many times. It had allowed it to occupy ecological niche in ecosystems of African rivers, earlier occupied by electric catfish (Malapterurus).
This catfish spends the most part of time at the river bottom. This fish inhabits shallow wood rivers and coastal area of large reservoirs. Electric synodontis keeps in places where small fishes and frogs - the basic forage of this predator – live in large number. Usually this fish hides in thickets of water plants or among driftwood, but at lack of shelters catfish simply can dig in layer of fallen leaves at the bottom. When in field of action of electric charge of this fish catch (fish up to 20 - 30 cm long, or frog) appears, catfish actuates the weapon, and after some seconds prey already fall on bottom, convulsively pulling. For a short time the catfish shows itself from shelter, grasps the paralyzed catch, and quickly swallows it. After hunting it needs time to have a rest and restore charge in electric organ.
But in spawning season these fishes do not hide at all, making courtship rituals. Males actively care for females, driving them by two – three ones. At this time cryptic colouring gives up the place to bright colors: throat and chest of the male become bright red, the body background brightens, and stains appear on it with the greater intensity. During caring males utter series of clicks and scratches with the help of spikes in pectoral fins. To the moment of spawning at females sides turn pale and become rounded from roe. More clearly female shows the readiness to spawning, more strongly the competition between males for the right to spawn with it proceeds. Males push away each other, sometimes put to the contender bites or grip its wattle. Eventually only one male will stay with the female, fertilizing spawned eggs.
At synodontises of Holocene epoch fishes more often simply dropped eggs at the bottom and did not care of it any more. In Great African lakes some species of synodontises simply put eggs stealthily for incubating to other species of fishes. Electric synodontises care of own posterity independently: female digs fertilized eggs in sand at the river bottom and protects a place of clutch within approximately week. All this time it eats of nothing. Being attacked by predators (more often it is large turtle or lizard), it protects future posterity with the help of impulses of an electric current.
Development of eggs proceeds about three days. But after hatching larvae sit in sandy nest approximately equal time, yet their yolk sac is resorbing. At hatching time the female by strong jet of water from mouth washes away the top layer of sand, accurately gathering by mouth and putting to the nest casually dropped out helpless larvae. After yolk sac resorbing larvae abandon nest for ever. They hide in thickets and eat small invertebrates. First some months of life their electric organ is not advanced, and they perish in great number from every possible predators, including from adult individuals of the same species. But at length about 6 – 8 cm they are already able to stun by charge fry of other fishes at the distance up to 10 cm. And special “signal of identification”, submitted by them at a meeting with neighbours, helps to avoid attack from the side of adult fishes. If the young fish succeed to survive, to the end of third year of life its length will reach one meter, and it’ll take part in spawning.

Root turtle catfish (Cystobiichthys radicans)
Order: Catfishes (Siluriformes)
Family: Pencil catfishes (Trichomycteridae)
Habitat: large rivers of South America – Amazon and Hyppolite.
Some groups of invertebrates are submitted exclusively by parasitic forms – for example, classes of tape worms and trematodes among flat worms, orders of fleas and lice among insects. In other groups representatives of few separate genera or species in the group submitted by free-living forms are parasites. Among vertebrate animals parasitic forms are rare exceptions. In Neocene only some mammals and birds turned to haematophags. In fresh waters of South America there is a blood-sucking species of neotenical tadpoles. But parasitism is most typical for fishes among vertebrates. Some catfishes of pencil catfish family are blood-sucking parasites, and among them in Neocene absolutely fantastic forms had evolved.
In cloacal bladder of elasmosaurine hydromedusa and other large turtles of South America one species of these catfishes parasitizes – the root turtle catfish, worm-like creature about 8 cm long. This fish lives in cloacal bladder and in adult condition leads sedentary habit of life. The parasitic way of life had leaved an imprint to anatomy of this catfish. It is blind depigmentated fish with transparent body through which walls interiors are visible. On stomach of fish the longitudinal plica of skin forms a line of suckers. This species eats exclusively blood of turtle – fish bites through epithelium of cloacal bladder and sucks blood, having densely attached by lips to wound.
One attribute gives out the presence of this parasite in turtle’s body: the long and strong shoot of tail fin formed by elongated fin rays and extending at the tip as a blade is put out from cloaca of reptile. It is penetrated with blood vessels, and through its surface gas exchange proceeds. The additional source of oxygen is blood of the turtle. This catfish has the special adaptation, permitting to extract oxygen. On the bottom side of body of the fish a plenty of fibers is developed; they take root into the epithelium of turtle (hence the specific name “radicans” meaning “taking roots”). Through them oxygen diffuses from blood of turtle. Due to uselessness gills of this species are greatly reduced, and branchial apertures are tightened by skin and are reduced up to two small holes above the bases of pectoral fins.
Pectoral fins of root turtle catfish have muscled bases, and the membrane between fin rays is reduced. Rays represent structures like claws with which help fish attaches to walls of cloacal bladder. Due to inhabiting inside turtle body this fish easily endures the necessity of turtle to go to the riverbank for egg laying. Therefore such catfishes parasitize in turtles of both genders.
Gender of root turtle catfish is not fixed genetically and may easily change in any direction depending on circumstances. Two any fishes appeared near each other in the same host animal turn to individuals of different genders and produce normal posterity. In connection with motionless way of life this species does not have courtship ritual and internal fertilization had developed. The cloaca of this catfish has ability to turn out and to extend as a tube. It forms similarity of penis at male and long extensible ovipositor at female. Male makes internal fertilization, and in ovoducts of female eggs start to develop. The female puts the ovipositor outside and lays fertilized eggs in water. At this time the embryo has already passed early stages of development. At absence of breeding partner fish develops as a hermaphrodite and lays normal fertilized eggs alone.
The fertility of root turtle catfish is rather big for such tiny fishes – within one week the female lays up to one hundred large eggs. Egg laying lasts some weeks in succession after one fertilization, and then female restores the physical condition, and male fertilizes it again. The young ones of this species lead strictly another way of life, rather than adult fishes: they are active planktonic predators eating fry of other fishes and also larvae of insects.
This fish species may exist as free-living stage for rather long time, reaching the length of 4 – 5 cm. At young individual in such condition eyes are well advanced; it is translucent and leads mobile mode of life for a long time, but at this time puberty is delayed. Frequently fish even dies “eternally young”, having not searched for host turtle and having not reached sexual maturity. Having found out a host turtle, catfish penetrates into its cloacal bladder and attaches to its wall. After the attachment the fast degeneration of unnecessary organs – eyes and fins – proceeds. On the belly side of body suckers and “roots” quickly develop, and then on tail additional respiring organ grows. For some weeks fish turns to true parasite, and then normally continues development and reaches sexual maturity. Too old individuals, however, can not go through such radical reorganization of an organism, and perish in body of host turtle.
Life expectancy of this catfish reaches 4 – 5 years.

Antiguan phoboclarias (Phoboclarias antiguae)
Order: Catfishes (Siluriformes)
Family: Airbreathing catfishes (Clariidae)
Habitat: fresh waters of Great Antigua – lakes and swamps.
In human epoch borders of faunistic and floristic areas appeared broken. People introduced various species of animals and plants to territory where these species could never appear by natural way. Frequently such activity resulted in degrading of ecosystems. Some of newcomer species had died out in epoch of global ecological crisis, but the part of species had survived, and their descendants had taken the place in ecosystems of Neocene.
In swamps and other freshwater reservoirs of Great Antigua Island one of descendants of animals introduced by people lives. It is the large catfish Antiguan phoboclarias, the descendant of clarias (Clarias batrachus) introduced from Asia to Florida. In human epoch clarias had got out of human control and had widely settled in freshwater reservoirs of Florida. In ice age this fish had got from Florida to Cuba, and then by temporary land bridges over small islets had reached islands formed Great Antigua in Neocene.
Antiguan phoboclarias is very large predatory fish (hence the name meaning “awful clarias”). The length of adult fish may reach two meters and even more (male is smaller and more graceful, than female). Body is very much lengthened, flexible and cylindrical. Low back fin lasts at all its length. Tail fin of fish merges with anal one. The skin of phoboclarias without scale is covered with plentiful slime. Colouring of this catfish usually is sandy yellow with small spots; stomach is white. Depending on color of environment this catfish can change colouring – on dark ground it turns dark brown with black spots. Change of colouring proceeds within several days after resettlement of catfish to other place.
Head of phoboclarias is flattened and wide. If necessary it may be used as a weapon – by impact of head the catfish is able to cripple animal swimming in water which it wants to eat. Due to wide mouth phoboclarias easily swallows chicken-sized animals.
This fish has badly developed sense of sight; small eyes are located on edges of head and are slightly shifted upwards. Bad sight at fish is filled with chemical sense – around of mouth of phoboclarias eight wattles about one meter long grow, and their surface is covered with set of receptors.
In pectoral fins of catfish spikes with poisonous slime grow. One prick of such spikes is enough to kill large dog-sized animal; therefore adult phoboclarias does not have enemies.
Phoboclarias, similarly to the majority of catfishes, does not like to swim long. It is a passive ambuscader trapping prey, having buried in ground almost completely. At the hidden fish only long wattles and a part of head with eyes is out of ground, therefore it is difficult to notice it among plants. When the fish or other prey of suitable size swims near, catfish rushes out from sand and catches it. Usually phoboclarias eats small fishes, aquatic insects and their larvae, frogs and tadpoles. But at an opportunity this fish eats animals got in water during flooding or crossing the reservoir. Also phoboclarias hunts ducks and other waterfowl. Hunting birds, it hides under leaves of water lilies and waits while the careless bird will move nearer to it. At this species cannibalism is advanced, and a significant part of posterity passed to independent life may be eaten by own relatives.
Phoboclarias is able to live almost in any freshwater reservoir with water of any quality. If in water there is no oxygen, approximately once per twenty minutes fish emerges to water surface and takes in mouth an air bubble – from it oxygen for breath is taken. It is especially important, if the fish lives in poor in oxygen water of swamp, in which there is plenty of rotten plants. From the ancestor, the clarias, phoboclarias had inherited the adaptation for breath by air – specially modified gills.
In rain season at fishes the courtship season begins. Its beginning is audible even at the coast of reservoir: male involves female, uttering melodious sounds – chirping trills. In shallow water it digs a nest – a hole about two meters in diameter and about half meter depth. Having cleared ground from dust, male begins courtship “songs”. It is very cautious at the presence of the female, and constantly keeps at some distance, always directing by head to her.
Fertility of the female makes up to 200 thousand of small eggs. After spawning male stays near the nest and protects eggs till five days, while fry will hatch. When fry will start to swim, male stays with them and protects the hatch during approximately two next weeks. At this fish the care of posterity is very strongly advanced: in case of danger male takes away eggs and fry in mouth. Also it acts so, if the reservoir where the nest is arranged dries up, or water level decreases. But it is only a part of that the adult fish can make for posterity. Clarid catfishes are able to creep overland, and phoboclarias can leave a reservoir, carrying away posterity. Keeping the posterity the adult catfish can creep overland till some days in searches of new habitats. During overland travel the body of fish becomes covered by viscous slime, helping to keep moisture; and in mouth eggs or fry become covered by liquid slime which slows the evaporation of water. The catfish feels a smell of water, and easily finds new reservoirs. If it had to move with eggs, in new residence it continues to incubate it in the mouth.
Young phoboclariases grow quickly, and at the age of about five years become sexually mature. Young fishes live in rich thickets of marsh vegetation where adult fishes can not eat them.

Eel-like serpentoglanis, snake catfish (Serpentoglanis anguilloides)
Order: Catfishes (Siluriformes)
Family: Airbreathing catfishes (Clariidae)
Habitat: Zinj Land, swamps and swampy lakes.
Clariid catfishes belong to the number of hardy and easily adaptable fishes. In the human era, some of their species were introduced to other habitats, where they got accustomed and began to harm the local fauna. The descendants of such fishes lived to the Neocene: one of them is the Antiguan phoboclarias (Phoboclarias antiguae), a giant predatory fish. In their homeland, these fishes also evolved, and the split of Africa promoted the isolation of populations and the increase of species diversity of clariid catfish.
In the swampy areas in the south of Zinj Land, one of the species of clariid catfishes lives – the eel-like serpentoglanis, or snake catfish. This fish is adapted to life in swamp water containing low amount of oxygen, thanks to the organs of air respiration – modified gills. The body length of an adult fish reaches one and a half meters, but the body shape is serpentine, the maximum body depth at this fish at the level of its belly does not exceed 7-8 cm. The low dorsal fin stretches along the entire upper side of the body to a short shovel-like tail fin. The pectoral and pelvic fins are short but strong; the pectoral fins are equipped with strong spines, serrated along the outer edge. The captured fish usually “quacks” loudly with its spines, wriggles and tries to strike with these spines. The slime covering the spines has a strong irritating effect and causes inflammation lasting several days.
The head of this fish is relatively small and flattened, with a wide mouth equipped with numerous small teeth. The eyes are small; there are small skin flaps near the nostrils. Like all members of its family, the fish has four pairs of wattles. The pair growing at the angles of the mouth is about twice the length of the head; other wattles are short.
The skin of the fish is scaleless and slimy, serving as an additional organ of gas exchange. The general color of skin is yellowish-green; the belly is white. Numerous brown spots are scattered on the back and sides; spots on the head are usually located closer to each other than on the trunk.
Eel-like serpentoglanis is a predator; it feeds on crustaceans, frogs and small fish, and sometimes catches the chicks of waterfowl. Usually the fish lurks among the bottom debris, occasionally surfacing for air. When prey approaches, the fish attacks it with a short rush and hides with it in a shelter, sometimes burying itself in the bottom sediments with its tail.
In conditions of stable moisture and constantly existing reservoirs, the fish remains active throughout the year. Only when they find themselves in shallow and low-feeding reservoirs, this fish undertakes a journey overland to neighboring reservoirs, guided by the presence of water vapor in the air. Like the Clarias catfishes of the human era, this fish is able to crawl on land, wriggling and clinging by the spikes of the pectoral fins. If the reservoir dries up, the fish simply buries itself in the ground, where it endures a drought at a depth of about half a meter in a rounded chamber, curled into a ball and hiding its head in its middle. At this time, gas exchange is carried out mainly through the body coverings.
In the rainy season, when the chemical composition of the water changes, the spawning season begins. The male of this species is slightly longer, but slimmer than the female. Fishes spawn in pairs, jointly digging a hole at the bottom of the reservoir, where the female spawns up to 30 thousand large eggs. During the rainy season, the spawning can repeat twice. After spawning, the male expels the female and takes care of the offspring, protecting the eggs and hatchlings during the first days of their life. At the age of 6-7 days, young fishes leave the nest and the parental instinct of the male weakens. At the age of 4 years, the young fish reaches a length of 70 cm and becomes sexually mature. Life expectancy reaches 20 years or more.

Wide-headed catfish (Silurus megachasmus)
Order: Catfishes (Siluriformes)
Family: Catfishes (Siluridae)
Habitat: Three-Rivers-Land, rivers of Fourseas basin, channels of large rivers and river shallows.

Picture by Alexey Tatarinov

During the ice age the majority of freshwater fishes of Europe had died out. There were only few representatives of them kept in lakes at the narrow strip between glacier and saline hollows at the place of Black, Caspian and Aral seas. And only few fishes managed to recede farther to the south – to Central Asia. There, in the rivers flowing from mountain glaciers, the rests of the fish population of Eurasia had found a shelter. Among them the true giant, wels catfish (Silurus glanis) predominated. When conditions began to change, fishes from the Central Asian rivers began settling to Europe.
Descendants of wels catfish were among these settlers. They had not changed too strongly externally, but had turned to true monsters – wide-headed catfishes. The fish about 5 – 7 meters long, weighting about 800 kgs, having huge head and strong tail, became the true tyrant of the large rivers flowing to Fourseas. Even the tsarfishes swimming up-stream for spawning, try to keep closer to each other when this monster swims near them. The width of head of large individuals of this catfish reaches almost one meter. Having huge mouth, fish swallows entirely animals as large as small deer.
Wide-headed catfish hunts large fishes, arranging ambushes at the river bottom of the. But it also includes ground animals into the diet, having turned to original ecological analogue of the crocodile of (temperate latitudes. The fish arranges ambush at the shoaliness and catches the animal had come to watering place, sharply jumping out from water, For such giant it is rather easy to mask: colouring of fish represents the set of dark brown spots on background able to change shade from green up to brown. Eyes of wide-headed catfish are small and located on edges of head. Therefore it is rather inconveniently to it to see prey directly. But it easily feels its presence due to the circuit of the electroreceptors covering its head. And also on head of a fish the circuit of channels of lateral line, catching movement of water, is advanced. So the wide forehead of fish represents an original “screen” in which everything occuring in front of head of fish is reflected. Wattles of this catfish are reduced up to small outgrowths – two ones on upper lip, two in corners of mouth, and four ones grow on the lower jaw.
To track down prey is not all yet. The most important is to catch and to drown it, if the catfish hunts ground animals. And this catfish has solved this problem. Having seized prey, it bends body sharply and throws prey above itself in water, and then, having turned around, pushes from riverbank by tail, snatches prey and drowns it. Its reliable support is the tail compressed from sides, along which the anal fin stretches from below. The part of fin rays has turned to strong prickles. Sticking them into the bottom, catfish provides to itself a support for a throw even at the oozy river bed.
Teeth at wide-headed catfish are very small; they grow on jaws in some rows. It is impossible to bite through prey or to cut off a piece of flesh with such teeth, but this lack is quite compensated by pressure force of jaws. Fish can easily crush chest of harelope or other animal of similar size by single bite. Though wide-headed catfish can catch even rather large ground vertebrates, its basic prey includes fishes, large frogs and waterfowl which it seizes from under water.
Like all catfishes, wide-headed catfish loves warm water and shows especial vital activity in summer. Then it catches ground animals more actively, trapping them at the watering place. This fish also spawns at higher temperature of water, in second half of spring. Male is smaller, rather than female (he is approximately one meter shorter), and differs from her in more sated colouring. To time of spawning he gets contrast colouring: back darkens, and stomach turns almost white with separate dark spots.
Spawning takes place at well warmed up sites of shallow water. Male chooses a site well warmed up by sun, pulls out all vegetation there, digs not deep hole and begins courtship “dances” near it – he whirls on this site, uttering loud rumbling heard even from under water. Spawning takes place at night and it may be very rough: fishes jump out of water and fall back with loud splash. Care of posterity is entirely male’s duty: he incubates clutch (up to 50 thousand grains of roe) and raises fry in mouth. The female lays eggs into the nest, and in the same place male fertilizes clutch, but right after spawning he banishes the female and takes away all eggs into the mouth. During the execution of parental duties male does not eat at all within approximately three weeks. Rather developed young fishes leave his mouth; they will reach maturity only at ten years’ age at length of about 3 meters. Life expectancy of wide-headed catfish makes up to 150 years.

This fish species was discovered by Simon, the forum member.

Namadzu catfish (Psammosilurus namadzu)
Order: Catfishes (Siluriformes)
Family: Catfishes (Siluridae)
Habitat: Hokkaido island (Japan), lower reaches of rivers of the eastern side of island.
The rivers of Japan Archipelago are short and have plenty of waterfalls and rapids. The complex relief of islands promotes occurrence of plenty of isolated habitats. But the same circumstance limits number of populations of fishes and the size of predatory fishes inhabiting the rivers of islands. Еру сonsequence of it is the variety of small species of fishes and rather small amount of large predatory species. One of the largest species of Japan fishes lives in the rivers of eastукт part of Hokkaido island where rivers form a circuit of channels and running-water lakes. It is the representative of catfishes named namadzu catfish. It is named after huge catfish from Japanese legends, which movements people believed the reason of earthquakes.
Namadzu catfish is the long-bodied fish capable to dig in sand fast. The size of this fish is up to 150 cm; body of fish is long and snake-looking. About three quarters of body length the tail stalk makes; it is ended with small tail fin merged with well advanced anal fin stretching along the bottom side of tail. Small back fin is located near to nape of fish.
Namadzu catfish perfectly masks due to colouring – background colour of body is brownish-yellow; on it the set of dark specks is scattered, forming chaotic marble pattern. Male and female do not differ from each other in colouring. Female differs from male in more heavy constitution and in greater length. Head of this fish is flat and wide, with small eyes located near corners of mouth. Sight sense at namadzu is very bad. The catfish receives the most part of the information on world around through wattles on which the set of chemoreceptors is located. Wattles of namadzu are long, and there are three pairs of them: pair of long wattles (half of body length of fish) in corners of mouth, and four short ones (not exceeding the length of head) on chin.
Namadzu catfish is inactive, and spends the significant part of time, having almost completely dug in sand and vegetative dust at the bottom of reservoir. This catfish is ambush predator and traps prey, having left on surface of ground only head and part of back. Despite of inactive way of life, it is the quite good swimmer. In open water namadzu swims, coiling the whole body like eel. But among thickets or snags this fish uses absolutely other style of swimming more similar to way of movement of South American gymnotid fishes (Gymnotidae and related families) – along anal fin waves move one by one, and fish moves forward, cautiously moving apart stalks of plants by head. If necessary the direction of wave movement changes to opposite, and fish equally easily swims a tail forward. With the help of movements of anal fin namadzu is dug in sand, from where jumps out to catch prey.
This predator eats small fishes, crustaceans and frogs.
The courtship season passes roughly. In spring when water gets warm enough, male starts “playing”, declaring rights to the territory with the help of jumps from water. When the female comes to his territory, male takes contrast spotty colouring and begins to court her, swimming near her and keeping the body in parallel to the body of female. From time to time male makes wavy movements, enabling the female to estimate force of his movements. The couple of fishes clears a site of bottom of dust and with the help of movements of anal fin digs furrow in it. The female lays in it some tens thousand small eggs, and male at once fertilizes them. After spawning female swims out, and male ventilates eggs with movements of anal fin, soaring above the nest. When larvae hatch, male looks after them for some time while they will be able to swim independently. When larvae turn to fry, male stays with them, and “pastures” school of young ones during approximately one week.
Young fishes at the end of the first summer of life reach the length 25 – 30 mm and pass to feeding on insects and other invertebrates. In two years the young fish reaches the length of about 40 cm and begins to eat almost exclusively fishes and small crabs. At the age of 4 years young catfish becomes capable to spawning, and lifespan of this species may reach 60 – 70 years.

Branchial suckermouth (Branchiolorica molligaster)
Order: Catfishes (Siluriformes)
Family: Suckermouth catfishes (Loricariidae)
Habitat: basin of Amazon and Hyppolite; the blood-sucking parasite on fish gills.
Parasitic species are very common among invertebrates – some large groups of these animals are present only by parasites. Parasitic vertebrates are rather the rare exception, than a rule. Among fishes representatives of various orders passed to partial parasitism, but most deeply specialized parasites were pencil catfishes (Trichomycteridae) known in human epoch. In Neocene some other kinds of sanguivorous vertebrates added to their number. The original branchial tadpole (Branchiosuga nosferatu), neotenical species of amphibians became the parasite. And among fishes one more parasitic catfish, the close relative of leechcatfish (Hirudistomus cataphractus), branchial suckermouth had evolved. It is small species of fishes – general body length of adult individual is about 5 cm. It eats exclusively blood of fishes.
Branchial suckermouth lives on gills of large fishes (for example, boltergillers (Potamocetus spp.)). It is kept on gills of host fish with the help of hooks growing on rays of pectoral fins. The mouth of all loricariid catfishes is transformed to sucker, and only few changes had been required for transformation of scraping mouth to sucking one. In mouth of branchial suckermouth sharp corneous plates grow. With their help catfish bites through an epithelium of gills of host fish, and sticks to the wound by lips.
The body of branchial suckermouth has lengthened shape and is flattened from above. It had undergone strong changes in connection with the adaptation to parasitism. The armour of fish is strongly reduced and represents very thin transparent plates which do not adjoin to each other on the back part of the body. The skin on stomach of fish is depigmentated, and through belly wall interiors and intestines filled with semidigested blood are visible. The top side of body is grey with cross black strokes. Strangely enough, at this parasite there are rather large shining eyes: it has good sight. Besides on front edge of head of this fish the set of the fleecy outgrowths covered with chemoreceptors grows.
Abdominal fins are rather small, but pectoral ones are strongly advanced – they are principal organs of attachment to body of the host fish. Front rays of pectoral fins are thick, covered with set of tiny corneous thorns, and the tip of fin ray is bent like a hook. Branchial suckermouth clings to gills of host fish by it. Unpaired fins are rather small; on bottom lobe of narrow tail fin there is long threadlike outgrowth.
This catfish does not live on the same fish constantly. It is able to swim and prefers to move from one fish to another at night when fishes are less active. If this catfish does not find suitable host, it may appear completely defenseless surrounded by various predators. Therefore branchial suckermouth having no host behaves very cautiously and secretively. In the morning it is dug in layer of fallen leaves at the bottom of river, or hides in long roots of floating plants, and keeps a full immovability, not giving out itself until the last second, or … yet will find out the host fish. Then catfish promptly attacks it and clings to its body behind the operculum. Having chosen a right moment, branchial suckermouth cautiously slips under the operculum of host fish, and attaches to its branchial arches.
These catfishes spawn during all year. When sexually mature fishes ready to spawning meet, they begin simple courtship ritual. Male cautiously sticks to the body of female, unfastens some seconds later and moves forward a little. It moves this way along the body of the female from tail to head, yet will reach her nape. Then he cautiously starts to slip to side of the female (because at this moment the female is attached to branchial arch of host fish, male actually slips downwards and appears turned the stomach upwards), and touches by abdominal fin the skin on her stomach. The female lays on stomach of the male about 20 – 30 eggs which stick to skin of the male. Male fertilizes eggs and cautiously moves them to its head. He bears eggs on fleecy outgrowths on edges of head.
Fry hatch after 6 – 7 days of incubation. The first days of life they keep on stomach of male, and he protects them from the current of water moving through gills of host fish. Within several days young fishes gradually leave him. They hide among underwater plants and eat algal scurf. Since the second month of life, at the length of about 1 cm young branchial suckermouths start to attack medium-sized fishes.

Cave suckermouth (Spealeoloricaria setosa)
Order: Catfishes (Siluriformes)
Family: Suckermouth catfishes (Loricariidae)
Habitat: caves of Yucatan, fresh water.

Picture by Tony Johnes

The family to which This fish species belongs is the most numerous in order and simultaneously looks the exception by food predilections among other families of predatory catfishes. Loricariid catfishes are very characteristic fishes of New World. After break of Panama Isthmus the part of species had remained in Central America where evolved independently from the majority of species had stayed in South America. Some species of loricariid catfishes had adapted to unusual habit of life: the parasitic species of these fishes is found in South America, and there is a sanitary species. But one species of Central American loricariid catfishes had settled under ground, in extensive calcareous caves of Yucatan, and had successfully adapted to unusual way of life.
Cave suckermouth prefers quickly flowing rivers and is especially numerous in places where the river current on ground surface hides in caves. In these places cave suckermouth finds enough food, being in habitual environment.
The shape of this fish shows the long history of settlement under the ground. Eyes of cave suckermouth are strongly reduced and are visible under skin only as dark spots. They are completely covered by skin and thin armour plates, and do not perceive light at all. In shape of fish presence of set of corneous bristles (hence the specific epithet “setosa”, meaning “bristly”) on lateral faces of head is remarkable. The armour at this catfish is kept: water in caves is strongly mineralized, and problem of armour construction does not arise. Neighbours of this species are crayfishes and crabs living in various caves, therefore additional protection is vital.
Body of cave suckermouth is strongly extended; it is about 15 cm long at the maximal width no more than 1 cm. At back edge of back fin at males the long string grows – it is strongly extended back ray of back fin. The same threadlike outgrowth is present at the bottom lobe of tail fin. Therefore catfish seems little bit larger, than actually is. The body of fish is colored pinkish white.
Pectoral fins at males and females are advanced equally well. At them there is a firm forward ray covered from the bottom side with set of frieze-like prickles. The bases of pectoral fins are shifted downwards. They are extended, lack of armour plates, and turned to strong suckers which keep this fish in rough underground streams.
Cave suckermouth has characteristic for loricariid catfishes scraping inferior mouth modified to sucker. This catfish eats bacteria and larvae of insects settling on stones. If in cave dead bodies of animals get from the surface, cave suckermouth willingly feeds on carrion. Also it eats bats had sunk in water which frequently drop from the ceiling of caves in which this species lives.
Caves differ in poor food resources, therefore populations of cave fishes are not numerous, and rate of breeding is very slow. But it is compensated by absence of large active predators; therefore the survival rate of posterity at cave fishes is rather great. Seasonal prevalence in spawning of cave suckermouth is absent, but breeding may repeat up to four times per year. Courtship games of these fishes differ in simplicity. Courting at the female, male keeps in parallel to her and by strong lateral movements of body turns waves to her body. The female estimates physical condition of the male by force of waves which it makes. Male broods a small amount of eggs (about 20 ones) in the mouth within several weeks; all this time it does not eat.
Young cave suckermouths become sexually mature at the age of about 10 months. Life expectancy of these fishes is no more than 6 years.

Mountain suckermouth (Platyhypostomus frigophilus)
Order: Catfishes (Siluriformes)
Family: Suckermouth catfishes (Loricariidae)
Habitat: Andes, mountain streams and cool rivers.
South America differs in large variety of catfishes; some families of these fishes are endemics of this continent. In Neocene when the climate became warm and damp, catfishes as many other freshwater fishes had started to evolve roughly and to develop new habitats. Andes, the high mountain ridge stretched along the whole Pacific coast of continent, became the house for some new species of fishes, including catfishes.
In cold quickly flowing water of mountain rivers, clean and rich in oxygen, large loricariid catfish – mountain suckermouth – lives. Length of this fish is about 40 cm – it is one of the largest representatives of family in Neocene epoch. This fish is perfectly adapted to life in fast current. The body of mountain suckermouth is strongly flattened; therefore when fish lays at the bottom, resistance to current is minimal. The shape of this catfish forces the current to press fish to the bottom.
Mountain suckermouth has wide head of rounded outlines with blunt snout. Small yellow eyes are shifted to edges of head and protected by bone “eyebrows”. Operculums are shifted to the bottom side of head. On the body of fish there are well advanced armour plates (it is the common feature of family), providing good protection against enemies and casual traumas against the stones moved by current. Colouring of body of mountain suckermouth serves for camouflage – it is grey with olive shade; on top side of the body there is “marble” pattern of cross irregular-shaped strips. When fish lays motionlessly on stones, it is almost not visible among patches of light at the bottom. Passive protection is the main vital strategy of this harmless fish. In case of danger mountain suckermouth prefers to hide at the bottom, and seeks safety in flight only at direct threat of life.
Unpaired fins of mountain suckermouth are wide and fanlike, with rounded tips. Tail fin of these fishes has colouring appreciable from apart: on dark grey background “trout” oculate spots, red with white border, are scattered. At large males this pattern is supplemented with white border on external edge of fin. These marks serve for warning of competitors and for courtship display. Also at males on bottom lobe of tail the long string formed by two strongly lengthened rays of tail fin grows. One more attribute of sexual dimorphism is characteristic for many representatives of loricariid catfishes, and mountain suckermouth is not exception here: at the male on edge of head long outgrowths grow; at this species they are appreciably corneous, firm and bristle-like. On forward part of head they are short; on each side of head they are much longer and grow in two lines, forming rich “whiskers”.
Pectoral fins of these catfishes are rigid and strong, with powerful front rays: they help fish to cling to stones. Fromt rays can be fixed in opened position, resting against stones, as an anchor.
The sucker-like mouth of This fish species is very strong; it helps to keep in current. Mountain suckermouth eats various kinds of food. This catfish scratches out from stones water mosses growing as pellicles, plants of Podostemaceae family, and also microscopic algae. Besides of plants mountain suckermouth eats larvae of insects – two-winged flies, dragonflies and caddis flies. Using wide head, catfish is able to overturn stones, searching for invertebrates. At an opportunity this fish eats dead bodies of animals had got in the river.
At the bases of abdominal fins of mountain suckermouth skin plica forms an additional sucker of semilunar shape. Using oral and belly suckers alternately and clinging by pectoral fins, this catfish is able to creep on stones, rising upwards in mountain rivers and even in low falls.
Mountain suckermouths spawn in places with weaker current, near stones, in underwater caves. Courtship games at them proceed not for long. Male displays to the female stretched back and tail fins, swimming in front of her head and from time to time pushing the female by side. Before spawning fishes keep in parallel to each other, and touch each other by tips of fins. The female lays eggs on bottom; male fertilizes them and at once gathers from stones, rowing up by outgrowths on head. In first minutes after fertilization jelly-like sticky layer starts to produce on the surface of eggs; with its help eggs stick to head of the male. Male broods eggs pasted to bristles from the bottom side of head till 8 – 9 days. Such speed of development of eggs is connected to low temperature of water in habitats of these fishes. Mountain suckermouths living in better warmed lower reaches of rivers rise upstream for spawning: at high temperature fry hatch weak. In first days of life fry keep on head of the male and sometimes escape from danger in its mouth. Till all brooding time male eats of nothing.
Young fishes become able to spawning at the age of two years, but active growth proceeds within first ten years of life.

Arafura mangrove catfish (Batrachoplotosus mangrophilus)
Order: Catfishes (Siluriformes)
Family: Stinging catfishes (Plotosidae)
Habitat: mangrove swamps of Arafura Lake.
Movement of lithosperic plate on which Australia and New Guinea are located, had caused rising of its northern edge. Arafura Sea had shoaled and gradually turned to extensive brackish lake separated from the ocean by multikilometer circuit of mangrove swamps and shallow channels. Salinity of water in them varies from slightly brackish during tropical downpours up to almost equal to oceanic one. In such conditions only few species of aquatic animals may exist normally – the majority of sea inhabitants does not endure fresh water, and freshwater animals do not suffer presence of salt in water. Nevertheless, there are fishes in mangrove channels. One of their representatives is Arafura mangrove catfish, the descendant of one species of sea stinging catfishes (Plotosus). When sea water began to turn fresh, the ancesor of this fish had not left it, and had adapted to life at coastal shallows, and then had moved to mangrove channels.
This species of catfishes is large eel-looking fish up to one meter long. The trunk of this catfish is compressed from sides, and the tail is bordered with merged back, tail and anal fins. With the help of strong tail fish can be dug in sand at outflow, and survive outside of water due to it till many hours. Head of this catfish is flat, with small eyes shifted to the sides. Wide mouth is surrounded with eight short wattles. This catfish has changeable colouring: in rest this fish is grey with numerous black spots on the top part of body, merging in twisting marble pattern on back and tail. Stomach and the bottom part of head at this catfish are white. At fright or at night black spots turn pale grey. In courtship dress male and female strongly differ from each other: female turns monotonously grey, and male has black back and sides, and white belly. On the background of black colouring its silvery eyes, surrounded with white spot, look especially impressively.
It is a predatory fish eating any prey, which it is able to seize and to swallow – smaller fishes, crabs and shrimps. Catfishes also eat animals fallen in water – mammals, reptiles and nestlings of small birds.
For protection against numerous predators living in mangrove forests, this catfish is armored with poisonous spikes growing in fins. This is a heritage got from ancestral species, which had been remarkable by their poisonness in human epoch. But in any case this species prefers to be imperceptible, and at danger is quickly dug in sand. Young fishes use this way of protection especially frequently.
As against to far ancestors lived at sea reeves in numerous schools, Arafura mangrove catfish is a solitary species, though it does not avoid the presence of congeners. It gathers to schools only for migrations connected to spawning. The adult fish lives in water of any salinity – from fresh up to oceanic water. But it spawns only in salt water, because too freshened water kills an embryo. For spawning catfishes wait for a time of the highest inflow in the month. With a tidal wave, filling channels of mangrove forest, adult fishes gather to schools and migrate to the depths of lake. At the depth of about 10 meters catfishes gather to shoals numbering many thousands of fishes, including individuals of both sexes. Within night fishes find each other, and courtship games begin in the morning. With the first rays of sun males turn black and white, and start to court after females. Competing for the female, males shove each other aside from her, pushing by sides. At this time their spikes are pressed to the body and are not used – their prick may be dangerous to congeners. During the courtship ritual male bites fins of the female and keeps near to her. The pair of fishes swims so till several hours, synchronizing ripening of eggs and soft roe. Directly to the moment of spawning the shoal is broken to the set of pairs.
Male and female throw up sexual products simultaneously, and male picks up by mouth large eggs – in clutch it may be up to 200 pea-sized eggs. Having spawned all eggs, females at once return to mangrove thickets, and males remain at spawning place. Male looks after posterity, brooding eggs in mouth. At this time males gather to schools and keep together at the distance from lake coast. They do not eat, and between them there is no competition, therefore in male school there are no fights.
The incubation lasts till about 50 hours, and some more days male carries helpless fry in mouth. In one week after spawning males swim up to the coast and let out posterity in thickets of aquatic plants. After that they return to rendered habitable places and do not care any more of posterity. At the age of 3 years young fishes become sexually mature. Life expectancy of this species makes over 30 years.

Scavenging loricaria (Carnoloricaria cornuta)
Order: Catfishes (Siluriformes)
Family: Armored (Suckermouth) catfishes (Loricariidae)
Habitat: tropics of South America, Amazon and Hippolythe basins.
In the era of man, loricariid catfishes formed the largest family in the Siluriformes order. Most of them were herbivores or omnivores with a bias towards vegetarianism. In the Neocene, some species of this group switched to feeding on animals – mainly small fish and crustaceans. One of their species – leechcatfish (Hirudistomus cataphractus) – feeds on necrotic tissues in the wounds of large fishes, rendering them the cleaning services. A related species, scavenging loricaria, switched to feeding on dead animal tissues – this species became a kind of underwater “vulture”. This fish inhabits slow-flowing rivers and lakes, avoiding swampy areas.
The length of scavenging loricaria is about 60 cm. The body of this fish has an elongated shape with a very long tail and short fins. The snout is short, flattened and rounded in outline. On the lower part of the head, there is a sucker-shaped mouth characteristic of the family, equipped with sharp corneous tubercles that allow it to scrape meat. Thanks to the movements of the mouth, the fish rubs the meat into a pulp and swallows.
The body is covered with several rows of bone plates. On the back and upper part of the sides, the plates are thickened and bear short sharp spikes. Such a reinforced shell protects the scavenging loricaria from other carrion-eating fishes that often show aggression to it. A “beard” of stiff corneous bristles grows on the head of the fish along the front edge of its muzzle; there are strong bone combs with a pair of vertically protruding spines above the eyes (hence the species epithet meaning “horned”). There are two more pairs of shorter spines between these spikes and the tip of the muzzle.
Rows of short bony spines grow on the tail stalk on its both sides.
Paired fins are triangular and pointed. The front rays of these fins are thickened and covered with many spines that help to stay in place. The dorsal fin is shifted backwards and is approximately at the level of the pelvic fins.
The body color of scavenging loricaria is catchy and noticeable: the snow-white background of the body with longitudinal coffee-brown stripes along the back and each side. The belly is yellowish in color. The fins are transparent, with white front rays and small brown dots on the surface. In the male, during the spawning season, the stripes turn velvety black, and the throat and belly turn lemon yellow.
Scavenging loricaria has a very keen sense of smell. Thanks to him, the fish is able to find carrion or dying animals (more often fish) at a great distance. The eyesight of this species is poor; the fishes are short-sighted. During feeding, these fishes can gather on carrion in larger or smaller numbers, being quite tolerant of their relatives. If the corpse is small, and there are many competitors (including ones of other species), these fishes “butt”, pushing them away with their muzzles and striking with “horns”.
The male of this species is larger than the female, with a large head and thicker front fin rays. The courtship season is not clearly expressed: reproduction occurs throughout the year. The male courts the female by sucking on her body and fins, and pushing her into his territory. There are up to 50 large eggs in the clutch. The female spawns eggs on a solid smooth substrate – a snag or a leathery leaf of a plant that has not yet had time to decompose. The male fertilizes the eggs and incubates them in his mouth for 3 days, while not eating anything. After spawning, he immediately drives the female away from his territory.
The first food of young fish is the epithelium in the male’s oral cavity: it swells and peels off from the oral mucosa as a multilayer film. Young fishes stay in the mouth of the male for up to a week, eating such food. Leaving his mouth, they immediately pass to independent life and feed on the clutches of snails and the corpses of small animals. Sexual maturity comes at the third year of life with a body length of about 40 cm. Life expectancy reaches 20 years.

Wood-eating plecotitan (Plecotitan xylophagus)
Order: Catfishes (Siluriformes)
Family: Armored (Suckermouth) catfishes (Loricariidae)
Habitat: the tropics of South America, Amazon and Hippolythe basin.
In the Neocene, the giant river basin in the north of South America was filled with sedimentary rocks even more than in the human era. This led to a reduction in the area of flooded forests and the division of the Amazon basin, from which the Hippolythe river separated. Nevertheless, the area of flooded forests is still large enough for fish species to appear that use the resources provided by the forest for life. One of the most peculiar fishes of the flooded forests of the Amazon is the giant phytophagous plecotitan catfish.
The appearance of this catfish is very peculiar: the fish resembles armored amphibians of the Paleozoic with its disproportionately large head and armored body. The body length of this catfish reaches 3 meters with a weight of over 400 kg. Plecotitan has developed a food source that is not available to most fish, and has achieved great success in this. Plecotitan’s food is rotting wood and all the organisms that live in it. In addition, this fish polishes the lower part of the trunks and roots of tropical forest trees with its jaws, stripping from them moss, epiphytic plants and fungi, as well as areas of rotten wood affected by fungi.
The body of the plecotitan is very massive and has a large belly holding a long intestine. The fish’s head is armed with mighty jaws and a sucker-shaped mouth. Sharp bone plates with constantly growing corneous edges allow the fish tearing off the upper softened layer of wood from sunken tree trunks along with the organisms growing on it. The head of the fish is deep; the eyes are shifted to its upper part. A pair of low bone ridges hanging over the eyes, pointing upwards and slightly to the sides. On the snout, there is a pair of thick conical horns that serve as tournament weapons. Sexual dimorphism is clearly expressed: males develop a “beard” of hair-like bristles on the sides of the head, and a “muff” on the anterior rays of the pectoral fins. The male and female have a similar color: the sides are brown with a pattern of intermittent convoluted horizontal lines mimicking the texture of tree bark. There is a similar pattern on the fins, but here the lines turn into rows of spots. Belly is light yellow with a small dark speck.
The intestine of this species is very long; passing through it, food is digested in great degree. In the feces of this catfish, almost 9/10 is wood dust, which is easily decomposed in water due to action of small invertebrates.
Being a large fish, plecotitan swims slowly. The fish has broad blunted paired fins with thickened front rays. The dorsal fin is deep and fan-shaped; in fish feeding in shallow water, it can rise above the water. The adipose fin is small.
The fish has highly developed means of passive protection: the bone plates on its back are very thick, and along each side, there is a row of plates with spikes up to 5 cm long sticking out sideways and slightly upwards. On the sides of the tail stalk, the spikes are longer, growing up to 10 cm. This fish defends itself from large enemies with a sharp blow of its tail, causing deep cut wounds.
This species is monogamous; spawning occurs once a year with the beginning of the rainy season. Courtship games are simple: the male splashes the water with his tail, demarcating his rights to the territory, and drives rivals away from the nest. Eggs develop in the hollows of trees or in “nest”, which the male bites out in the rotting tree trunk before the beginning of courtship games. The male guards the clutch and ventilates it with the movements of the fins. Clutch numbers up to 200 thousand eggs; a significant part of the offspring dies in the first weeks of life. About 5% of the brood survives until the end of the second year of life. Sexual maturity comes at the 5th year of life with a length of about 60 cm. Life expectancy is over 120 years.

Usambara characid trout (Alestotrutta ussambarica)
Order: Characids (Characiformes)
Family: African tetras (Alestidae)
Habitat: mountain regions at the east of Zinj Land, mountain rivers.
When African continent had broken up along the Great Rift Valley line, all highest mountains of continent had stopped to belong to it. They had remained at the subcontinent named Zinj Land. Because of global ecological accident many ecosystems appeared destroyed, but it almost had not affected terrestrial and fresh-water ecosystems. Flora and fauna of Zinj Land developed completely separately from Africa till at least approximately ten millions years, from the moment of separating of subcontinent from continent. The variety of freshwater species of animals had kept almost at former level. Characid fishes are very characteristic for continental reservoirs of Africa to the south of Sahara and for New World (South America and the south of North America). They inhabit various reservoirs – from stagnant swamps up to cold mountain streams. They avoid only brackish water.
Significant spaces of Zinj Land are occupied by mountain landscapes. One of characteristic species of fishes lives in streams with quickly flowing clean and cold water – large trout-looking characid named Usambara characid trout. It is a fish about 60 – 70 cm long with torpedo-like body and pointed muzzle. It swims quickly and can “stand” in fast current near stones or bushes of water plants for a long, similarly to trout.
The basic colouring of body of characid trout is silvery blue. Fish has narrow black longitudinal strip on body, stretching from tip of muzzle through an eye up to the basis of tail fin. Also at characid trout there is darker back making fish imperceptible on the background of bottom at sight from above. Back fin of fish has pointed tip. At the male the height of fin exceeds height of body. Tail fin is high and crescent; it also has rigid rays.
Characid trout is insectivorous predator. This fish hunts down insects flying low above water, and jumps to catch them at height up to one meter. Characid trout has large eyes – sight plays a leading role in air hunting. Also fish searches for larvae of dragonflies and caddis flies at the bottom of streams. Occasionally characid trout hunts down small fishes, including its younger congeners. The mouth of characid trout is wide – its cut lasts up to level of front edge of eye. Jaws are armed with numerous thin pointed teeth.
Characid trouts spawn in current, spawning very large amount of eggs – up to 200 thousand small eggs. Male at these fishes is larger, but more graceful, than female. Its colouring differs in more intensive blue shade which is amplified on head, passing to dark blue on tip of muzzle. On this background at the male silvery “ear-ring” spots at operculums are clearly visible. In courtship season (during the thawing of mountain snows) male actively chases females, pressing them by body to the bottom. If the female is ready to breeding, she swims near the male within several hours. At this time at fishes sexual products intensively develop. At night or in early morning spawning begins. Fishes splash in stream, jumping out of water, and male chases the female, biting her tail. Just before the dawn time fishes spawn eggs, scattering them in current. This fish species does not care of posterity, and as required adult characid trouts can be cannibals. The young ones differ in habit of life from adult fishes. Young characid trouts keep in thickets of water plants. At them bottom jaw is short, and mouth is inferior. They scrape off larvae of insects and bacterial cover from stones. The young ones also differ in cross-striped colouring. As they grow, the middle part of strips stays dark, edges turn pale and fishes gradually get “adult” longitudinal-striped colouring.
The first spawning of young fishes takes place at the age of three years at length of body about 30 – 35 cm. This species reaches the usual size to the age of six years, and then growth of fish slows down. At the age of 20 years some fishes reach length of 80 cm, but it is the extreme rarity. Usually life expectancy of characid trout does not exceed 15 years.

Mahamba (Mahamba mahamba)
Order: Characids (Characiformes)
Family: Distichodontids (Distichodontidae)
Habitat: Western, Central and Southern Africa, rivers and lakes.
The Neocene is a time when the world has changed a lot, recovering from the times of impoverishment of nature in Holocene as a result of human activity. However, people and their civilization have disappeared, and the animal world has undergone significant changes. Large aquatic animals, such as African hippos and crocodiles, have become extinct completely. They had been replaced by other creatures that had previously been in the shadow of giants – pigs, turtles, large monitor lizards. And by fishes too.
Among the fishes of the Earth, characid fishes were one of the most diverse order, uniting such different creatures as carnivorous piranhas and small peaceful freshwater hatchetfishes. In Africa, they were represented not only by omnivorous forms and peaceful vegetarians, but also by specialized predatory species. Among them there were, in particular, large solitary predators that were ecological analogues of crocodiles. The crocodiles themselves survived to the Neocene, but lost their positions as the top predators of fresh waters, especially in Africa, where they were replaced by various monitor lizards, and by the crocoturtle in the north. And in the west and in the south of the continent, their place was taken by the descendants of African characid fish Ichthyborus, among which mahamba is the most remarkable species.
Mahamba is a true giant among African freshwater fishes, reaching the length of about 5 m. This species lives in large rivers and lakes, and is the top predator of productive ecosystems of reservoirs. The body resembles the body of goliath tigerfish (Hydrocynus goliath) of the Holocene in shape – it is elongated, torpedo-shaped, with well-developed fins and a strong tail. The head reaches almost one and a half meters in length and partly resembles a crocodile’s one; the jaws are very elongated, narrow and mobile. When the fish opens its mouth, the upper jaw also rises. The teeth are pointed, piercing, especially numerous at the ends of both jaws – such teeth allow it to hold slippery prey. Eyes are large; the fish has good eyesight.
Fins are well developed; the caudal fin is deep and triangular. Back and anal fins are shifted to the posterior third of the trunk. There is a small adipose fin.
The color of the back is brown with darker spots forming a pattern resembling grooves on the tree bark. The sides are dark green with some rare light spots; belly is yellowish-white. Tail fin is mottled – 6-8 black horizontal stripes stretch along a light yellow background.
This fish is not remarkable in the complexity of behavior, but is very patient, and is able to wait for suitable prey for several hours, and even days, hiding in ambush – usually at a tree that has fallen into the water or in the shade of branches of large trees. When a suitable prey appears, a quick rush from an ambush follows, and the prey is either swallowed whole, or mahamba inflicts one or more extensive wounds on it, causing its prey to either drown or bleed and die from pain shock. The usual prey items of this species are fishes, amphibians and reptiles, as well as waterfowl and mammals weighing up to 20-30 kg. At the same time, the fish avoids attacking turtles protected by strong shells. Young fishes often attack waterfowl, swimming on their sides just below the surface of the water, and dragging the bird under the water with a sideways movement of the head.
Mahamba is a solitary predator; sometimes there are episodes of cannibalism, but adult fishes rarely attack each other. Usually the conflict is limited to standing head to tail of the opponent, and displaying of tail fins. The low metabolic rate leads to the fact that mahamba rarely eats and digests prey for a long time; therefore it does not require an extensive feeding area and prefers to simply avoid the company of congeners. This species also does not have an expressed spawning period, and at any time of the year individuals ready to spawn may be found.
Courtship ritual is quite simple: the male swims around the female and displays his physical condition to her, shaking his whole body and driving waves on the female with his tail. However, he is on guard, and is ready to retreat at any moment if the female shows aggression. If he matches the female, then she gives a signal, moving her pelvic fins in a special way. Spawning itself happens quite quickly, and the fishes do not show any parental care – they only bury large eggs in a layer of rotten leaves at the bottom of a river bay with a slow current. Fertility is up to 300 thousand eggs. Fry hatch already quite large, and grow relatively quickly – in the first year of life, they reach a length of 20-25 cm. This species has a high mortality rate of offspring, including due to cannibalism. Only after they reach at least 75 cm in length, they become more protected from other freshwater predators – it happens at 6th-7th year of life. At the same time, young fishes become capable of reproduction, but full participation in spawning is possible only at the age of 12-15 years. The average life expectancy of a mahamba is several decades, usually up to 50-60 years. Single individuals can live up to the age of a century.

This fish species was discovered by Bhut, the forum member.

Pennant-finned harpagognathus (Harpagognathus callopinnus)
Order: Characids (Characiformes)
Family: Distichodontids (Distichodontidae)
Habitat: Central Africa, Congo basin.
Changes in the Earth’s biosphere at the turn of Holocene and Neocene led to a large-scale change of top predators in ecosystems. Freshwater ecosystems suffered mainly from indirect results of human activity – deforestation and pollution of rivers, as well as the introduction of new alien species. In the Congo river system in Central Africa, large predatory fishes disappeared along with crocodiles, but in early Neocene, their place in ecosystems was taken by the descendants of small zoophagous species. Some of them turned to large loners, while others have chosen the tactics of schooling predators capable of jointly killing and eating large prey. Among these species is pennant-finned harpagognathus, a schooling hunter of medium-sized fishes and other vertebrates.
The appearance of harpagognathus indicates its ability to move quickly. It is a fish about 30 cm long, with an elongated torpedo-shaped body and a sharp-nosed head with large golden eyes and wide-opening mouth. Body color is silvery-green with a longitudinal stroke along the lateral line extending from the tip of the snout to the base of the tail fin. Sometimes a second stroke stretches parallel and above it. Back is dark; belly is silvery. Fins are pointed and transparent, except for the dorsal fin. Dorsal fin is deep (its depth exceeds the depth of the fish’s body) with a pattern of alternating horizontal black and white stripes. Such a fin allows fish to recognize relatives and gather in school to search for food. Adipose fin is small.
Harpagognathus is an exclusively carnivorous fish species. Due to the special anatomical features of the jaws in carnivorous representatives of its family, when opening the mouth, the upper jaw rises, allowing them to bite out a larger piece. The teeth are bicuspidate, of cutting type – during the feeding, they easily cut off pieces of meat from the prey. The front 2-3 pairs of teeth in both jaws are slightly larger than the rest ones, making deep incisions with each bite.
Harpagognathus schools number up to 50 individuals, and are able to gnaw to the bone easily an animal weighing about 15 kg. These fishes hunt large fish, turtles and waterfowl. After intensive feeding, fishes lose interest in hunting for a long time and hide in deep pools, digesting their prey.
An interesting feature of this species is the ability to recover from significant damage to the skin, muscles and fins – this is an adaptation to life in a school of aggressive relatives. Wounded individuals usually leave the school and heal wounds in shelters, after which they rejoin a school of congeners of a suitable size.
Spawning takes place in schools and repeats 2-3 times a year; each female spawns up to 50 thousand eggs. Usually, in fishes from the same school, reproductive products form synchronously. Spawning takes place in the early morning in the thickets of small-leaved underwater grassy plants. Fishes spawn their eggs over a vast area, and do not care about the offspring. Fry feed on insect larvae and small fish. In the second year of life, they grow up to 15-18 cm, and become capable of reproduction. Life expectancy does not exceed 10-12 years.

Rostrophago, Congo tweezers fish (Rostrophago gavialorostrum)
Order: Characids (Characiformes)
Family: Distichodontids (Distichodontidae)
Habitat: Congo basin, small forest rivers.
Representatives of the Distichodontidae family include not only herbivores, but also specialized predatory fishes of fresh waters of Africa. Some of them turned into large forms, while others, on the contrary, greatly decreased and became specialized hunters for small prey. These species include the tiny rostrophago, or Congo tweezers fish. It is a fish that reaches only 55-60 mm in the adult condition. Body is very elongated and wedge-shaped – with a thin snout, reaching a maximum depth at the beginning of the last third of the total length, and narrowing relatively sharply to the tail. Dorsal and anal fins are lobe-shaped; adipose fin is small. Tail fin has wide blades.
Jaws are elongated into long “tweezers” set with bicuspidate teeth. At the tips of the jaws, the teeth are elongated; along the entire length of the jaws there is a row of small piercing teeth. The jaws can open wide, since both jaws are mobile in predators of the Distichodontidae family.
The body color of this species is cryptic – brown with an intermittent yellow stripe above the lateral line stretching across the eye; there are several dark spots on the back. Fins are transparent.
Congo tweezers fish is a small solitary predator that prefers to live in heavily overgrown rivers with a slow current. The basis of its nutrition is insect larvae: the shape of the jaws allows it to take them from the bottom sediments. In addition, this fish eats fish eggs and fry, tadpoles and worms. When searching for food, this fish swims head down, with the help of waving of back and anal fins. Each individual occupies a certain territory, which borders are strictly guarded. In case of danger, it takes a horizontal position, and swims away into the thicket, abruptly changing the direction of movement, or rushes to the bottom and buries itself in plant debris. When attacked by an enemy of comparable size, this fish can bite.
Spawning season is not expressed; reproduction is possible all year round. The breeding pair is formed carefully: the fishes stay on the borders of their territories for a long time, and gradually get used to each other’s presence. Spawning occurs in thickets of small-leaved underwater plants. Fertility is up to 300 eggs; parents do not protect the clutch. Reproduction occurs 3-4 times a year. Young fishes are capable of reproduction at the age of 7-9 months, life expectancy is up to 4 years.

Barracuda phago (Necrophago sphyraenoides)
Order: Characids (Characiformes)
Family: Distichodontids (Distichodontidae)
Habitat: Congo, middle part of river channel.
Among inhabitants of African rivers characid fishes are very typical. They are less various, than species in South America, and occupy slightly other ecological niches. Among them there are many predatory species, and omnivorous and herbivorous ones frequently differ in large size. Small predatory fishes of genus Phago had occupied the special place among African characids. These creatures distinguished by furious and predatory behavior, had survived in mass extinction – being small fishes, they could keep rather numerous population till the falling of biological efficiency of reservoirs. Large river predators died out till the ice age – this process had completely exterminated crocodiles, for example. But after stabilization of environment conditions at small fishes the tremendous chance to force the way into large-sized class and to be among succeeding predators of Equatorial Africa rivers, competing with predatory turtles and lizards, had appeared.
Length of Phago and most part of its congeners of Holocene epoch did not exceed 20-30 cm. But their descendant, huge barracuda phago, became frightening inhabitant of Congo. It is the predatory fish reaching length up to 2 meters. Body of this predator is lengthened and streamline-shaped. Barracuda phago may accelerate large speed and easily resists to strong current. On sides of this fish body is covered with armour of thick scales – barracuda phagos are rather aggressive relatively to each other, and this adaptation for protection in intraspecific skirmishes is not superfluous for them. Scales form set of slanting cross lines on sides, and the body keeps sufficient flexibility and mobility.
Fins of barracuda phago are short and peaked, and fatty fin is very small. Unpaired fins are shifted to the back part of body – such feature is characteristic for fishes making fast throws. Tail fin of barracuda phago is high and rigid, adapted to accelerating of fast speed.
Barracuda phago has kept a diet, characteristic for ancestors: it is active predator. At it there is big head with long jaws on which numerous pointed teeth stick up. Due to the size this fish eats any animals which it may find in the river and swallow: fishes, shrimps, waterfowl and small ground animals had got in water. For this species cannibalism is very characteristic, therefore young fishes avoid meetings with adults: they keep in shallow rivers, mastering main channel till the process of growth.
Young and adult fishes have different ways of life and thereof at them the various colouring varying in process of growth was developed. Young fishes are more secretive, than adults: they spend a lot of time, hiding among roots of floating plants near the water surface. Therefore their colouring is cross-striped: on silvery background rough vertical strips stretch, hiding fishes among roots of plants. Adult fishes keep in river channel where there are not enough bushes of floating plants. Their body has monotonous silvery colouring.
Being a predator, barracuda phago is solitary fish. Each individual has extensive fodder territory in river channel and actively protects it from neighbours. Threatening the neighbour, the fish utters series of loud creaking sounds well heard from under water. If the contender does not abandon the occupied territory, fishes enter fight: they put bites to each other, drag each other by jaw and tear contender’s fins. Sometimes one of fishes may even kill the contender.
The loneliness of barracuda phago is broken in spawning season. Spawning at this species is schooling, as at many others characids: at this time all borders of individual possession are broken, and predators gather in large shoals numbering up to fifty adult fishes. Unique rescue for river inhabitants at this time is that during spawning the food behaviour at barracuda phago is suppressed. Therefore in shoals of adult fishes it is possible to find young fishes not yet completely left striped colouring.
During courtship games males pursue female by small group, uttering abrupt single clicks. At the culmination moment they densely nestle against the female from different sides, literally squeezing eggs out from it. Small transparent eggs are spawned in water, at once are fertilized, and males lose interest to the female. They abandon it, and start to drive other females, yet not spawned eggs. Having spawned eggs, females try to get rid of chasing from the side of males: they leave the common shoal and hide in thickets of floating plants, as if young growth.
Eggs develop in thickness of water, being gathered at coast or among small bushes of floating vegetation. The incubating lasts about 2 days. Larvae passively soar in thickness of water, becoming prey of various plankton crustaceans and small fishes. But part of them turns to fry a day after. Fry actively swims and hides among plants floating on water surface. Part of them perishes, when the watercourse carries away thickets of floating plants to the ocean. But some of them succeed to survive among thickets, washed to river banks. Growing up, young barracuda phagos migrate in rivers then to return to main channel as one of main predators of the river. They become sexual mature at the fifth year of life, at length about one meter. But at this time at them striped colouring is still kept. They completely develop and lose juvenile colouring up to seven years. Life expectancy of barracuda phago may reach 30-35 years.

Comb-jawed duckweed-hackler (Exodolabrus lemnivorus)
Order: Characids (Characiformes)
Family: Comb-lipped characids (Ctenolabiidae)
Habitat: Congo basin, lakes, bays and cutoff meanders.
Characids are one of groups of fishes common for Africa and South America. Though at these two continents even common families of these fishes had not remained, the relationship of African and South-American characids indicates former connection of Old and New World. In Africa the majority of characids is presented with predatory or omnivorous species, but representatives of citarinids family (Citarinidae) are exclusively vegetarians, despite of competition from the side of numerous cyprinid fishes. Till the ice age in equatorial zone of Africa many representatives of aborigial tropical fauna had been kept, and life in this place had always differed in variety. Therefore narrow food specialization had become the best solution in stable environment at rigid competition. In such conditions some African characids had turned to stenophagous species.
One of narrowest food specialists among herbivorous fishes of Africa is the comb-jawed duckweed-hackler. It is rather large fish reaching length about 30 cm. Duckweed-hackler constantly keeps near to surface of water; in this connection its body has got rather characteristic shape. The top part of body of this fish is flattened; head and back make practically straight line. The bottom part of body of duckweed-hackler, on the contrary, has rounded outlines. The body of fish is strongly compressed from sides due to what duckweed-hackler easily squeezes among roots of floating plants hanging down in thickness of water.
Tail of this fish is short and wide: duckweed-hackler does not like to swim far, but in case of necessity it can accelerate large speed, escaping from predators or arranging courtship display. Back fin of fish is short and triangular; flesh fin is low. Wide anal fin of this species has the important role in displays: having stretched and colored it brightly, male involves females, swimming near the surface of water.
The body of fish is colored yellowish with brown irregular-shaped spots and pale “leaf nerves”. In case of danger fish skilfully simulates rotten leaves, rushing on bottom and quickly digging in dust. When silt and settle sediment, the hidden fish becomes invisible. Duckweed-hackler can hide in bottom dust for some minutes. As a rule, it is enough, that predatory fish ceases to search for it.
Duckweed-hackler eats exclusively one kind of food: duckweed covering like continuous carpet the surface of tropical reservoirs. The mouth of this fish is perfectly adapted to such diet: it is shifted and oblique upwards. Top jaw of duckweed-hackler has a remarkable structure: teeth on it are very thin and numerous, forming true “palings”. They stick up on the internal surface of upper lip, and when the mouth is opened their edges are directed upwards and a little forward. Bottom jaw with thick fringy lip at the opened mouth is directed in parallel to water surface. Eating fish “draws” water surface by upper lip, gathering duckweed by thin teeth, as if like net. From time to time it closes mouth, and lower lip rakes gathered duckweed from top jaw and fish swallows it. Duckweed is rich in protein, but fish also eats tiny animals settling on duckweed.
Duckweed-hacklers protect the fodder site actively, and support it in cleanliness: they tear off leaves of water lilies and take away large floating plants, releasing living place for growth of duckweed. Each fish owns the certain site on water surface (approximately some tens square meters). It drives off congeners from site, showing itself in ray of sun light. However, at edges of fodder territories at these fishes necessarily there is secluded nook in which duckweed-hackler hides from predators.
In spawning season duckweed-hackler does not show strict intolerance to congeners. Females have a right to swim to another's territories, and males do not hide their location – they highly jump out of water, ploping down back loudly splashing. At duckweed-hacklers males are smaller than females, but they have larger head and are colored brighter. Courting after the female, male spreads anal fin on which the border of red color appears, and shows itself in sun rays. Preliminary it scatters plants floating on water surface to make the place of display lighter.
As against to the majority of citarinids and their relatives, duckweed-hacklers spawn in pairs. Male drives female above the bottom, and from time to time presses it to underwater objects. Sires spawn transparent not sticky eggs in water, and it sediments on bottom. Fertility of one female may reach 30 thousands of eggs. Adult fishes may eat a part of eggs, picking them up during the spawning act, but after spawning male banishes female and swims up to the surface of water. Therefore the significant part of eggs has an opportunity to develop at the bottom among dust.
Incubating lasts about two days, and about day larvae motionlessly hang on plants. Then they turn to fry and start to eat phytoplankton and protozoans. Till the first year of life young fishes reach length of 4 – 5 cm and win to themselves small fodder territories, usually in shallow water where adult fishes do not swim. Approximately to the third year of life duckweed-hackler reaches the usual size of adult fish and becomes able to spawning.

Carpentary Pseudopiranha (Pseudoserrasalmus lacustris)
Order: Characins (Characiformes)
Family: Piranha and Pacu (Serrasalmidae)
Habitat: Lake shallows and upper layers of Carpentary lake, thickets of aquatic vegetation.

Picture by Lyagushka

Sometimes the needs of man outweighed the needs of nature. In Papua New Guinea, the decision was made to introduce Pacu (genus Piaractus) to local waterways in order to provide an abundant food fish to local native tribes. Soon this pugnacious fish not only had a negative impact on local ecology, but also began attacking fishermen who waded or bathed in the rivers. The success of the introductions proves its viability even in the absence of man, and a descendant of this is found in the CarpentaryLake, Pseudopiranha.
Carpentary Pseudopiranha is a mainly carnivorous fish reaching 80 centimetres long and weighing up to 5.3 kilograms. Unlike a true piranha it does not shoal, and it somewhat lacks the ferocity of these fish. In color and shape it resembles a slightly more elongate version of a piranha, with silver grey scales, and a yellowish belly. The face is not as “bulldog” as its relatives, and the jaws protrude somewhat to form a square “snout”. The extremities generally resemble those of a typical piranha, and it is built for short pursuits. This fish will feed by hunting and killing smaller fish with hurried vicious bites. Teeth are robust and blade like, with 3 points, and jaws are powerful. Sometimes this fish will steal bites of the fins or extremities of larger fish, though usually it only kills fish smaller than itself, frogs, insects, worms and crustaceans are also eaten. Though they are generally solitary, they will congregate to scavenge submerged carcasses. As with its ancestor, it will also occasionally eat fruit that falls into the water. This fish is mainly diurnal, sheltering in dense thickets of submerged vegetation at night. They are able to call by using the sonic muscles of their swim bladder, and will produce a small drumming noise when agitated or feeding.
These fish are sexually mature by one year old, and spawning occurs in the wet season. Pairs will form, and they will swim parallel to each other in a courting display. During this time, the female will lay several thousand eggs in a shallow nest, attached in sticky masses to the bases of submerged plants, these are then fertilized by the male. Both male and female will guard the nest until the fry hatch. Within a few days, these babies then hide amongst water vegetation until they are large enough to fight back. Eggs are sometimes consumed by other kinds of fish, or aquatic birds. The adult fish will sometimes fall prey to larger fish, crocodiles, snakes and raptorial birds. Individuals can live as long as 10 years.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Patagonian roachsalmler (Characorutilus notalis)
Order: Characids (Characiformes), or Cypriniformes (Cypriniformes), suborder Characeae (Characoidea)
Family: Characids (Characidae)
Habitat: rivers of the southern part of South America.
In the age of man, characids were the dominant group of freshwater fish in South America. Among them, there were both small and fairly large species that occupied a variety of ecological niches – from insect-eaters and herbivores to active predators. Most of these fishes inhabited the well-warmed waters of the tropical and subtropical regions of the continent, and only a few species lived in cold waters – mainly in the highlands. Climatic changes at the turn of Holocene and Neocene caused a reduction in the range and a decrease in the species diversity of the thermophilic ichthyofauna. However, some representatives of characid fishes managed to adapt to the colder conditions, and when the climate stabilized, they retreated to the south, following the glaciers.
In the far south of South America, there are several species of fishes that have adapted to the cool seasonal climate. One of the most common species is the Patagonian roachsalmler, a large species of characid fish. Compared to most human era characid fishes, it looks like a giant: the length of an adult from the tip of the snout to the rear edge of the tail fin is about 30 cm. It is a good swimmer with a streamlined muscular body and a strong tail. The head of the fish is relatively large, with a wide-opening mouth. Jaws are equipped with sharp cutting teeth. Tail fin is two-lobed with an expressed notch on the posterior edge. Pectoral and pelvic fins are pointed. Dorsal fin is deep with slightly elongated anterior rays. Adipose fin is translucent and small.
The body color of Patagonian roachsalmler is inconspicuous – silver-gray sides and belly, dark brown back. In fishes living in swampy reservoirs, the brown color spreads on their sides. Fins are light orange; the dorsal fin is colored brighter than the others: it is reddish-orange with a narrow white border. During conflicts, fish opens it and displays it to the opponent. Eyes are large, with a silvery iris.
Females are more massive than males; dorsal fin is much paler colored in them. They also differ from males by a more rounded bellies swelling strongly by the time of spawning.
It is an omnivorous fish species found in rivers and lakes in southern South America in schools of up to 20 fishes. Usually fishes keep in coastal shallow waters, eating soft underwater vegetation and invertebrates. If possible, fishes willingly eat carrion. Wintering takes place in underwater pools and deep areas of riverbeds. At this time, fishes are inactive and almost do not feed. They keep in schools, and up to several hundred fishes gather in one wintering place at the same time.
Spawning begins in spring, when snow melts in the mountains, and rivers overflow their banks. At this time, males become much more aggressive towards each other, turn colored much brighter and chase females violently. Spawning occurs on a clear day when the coastal shallow waters are well lit. A school of fishes swims in shallow water, and excitement gradually increases in it. When the sun rises high above the horizon and brightly illuminates the coastal shallow waters, fish school gradually splits into pairs, in which the male actively chases the female and presses her against rocks and thickets of plants, forcing her to spawn a portion of eggs, which he immediately fertilizes. The fertility of one female is up to 100 thousand small transparent eggs. Eggs are randomly scattered on the river bottom, rocks and plants, and some of it can be eaten by adult fish from other pairs. Fry hatch at the third day, and after another day they begin to swim and eat. Young fishes keep in numerous schools; mortality rate is high among them, especially at an early age. Sexual maturity comes at the age of 2-3 years, and life expectancy reaches 15 years or more.
In the far south of South America, a close species lives – sleeping roachsalmler (Characorutilus hibernator). It is much smaller: an adult fish is only about 15 cm long. It has a greenish-silver body color and brownish-red fins. It is an omnivorous species that lives in small schools in non-flowing reservoirs – in swamps and swampy lakes. In winter, when reservoirs freeze, this fish buries itself in a layer of silt and falls into a dormancy, waking up only in spring. In deep lakes, these fishes overwinter, gathering in deep places in numerous schools.

Black Amazon characid pike (Piranu serrasalmiformis)
Order: Characeae (Characiformes)
Family: Pencil fishes (Lebiasinidae)
Habitat: South American rivers and lakes.
As a result of anthropogenic pressure of the Holocene epoch and climatic changes of the early Neocene, many animals of the Earth became extinct, especially large and predatory species sensitive to habitat changes. Among them, there were crocodiles and caimans, once being among the largest thriving reptiles of the Earth. In the Neocene, their descendants are very unnumerous, and the vacated ecological niche was occupied by species of other systematic groups. In the Old World, these are other reptiles – lizards, snakes, and even turtles, and in South America – various fish, mainly of the Characiformes order. One of the largest species is tyrannocharax (Tyrannocharax deinodontus), a representative of the Erythrinidae family. However, other fishes have also evolved rapidly, occupying accessible ecological niches.
Black Amazonian characid pike is not a true pike, but a descendant of one small species of insect-eating fishes of Lebiasinidae family, which has successfully mastered a predatory lifestyle. In appearance, it looks like a mix between pike and African tigerfish (Hydrocynus) of the Holocene epoch. It has a long, somewhat laterally compressed body, and a wide tail fin, which allows this fish to make quick, sudden rushes. Other fins are also well developed, which allows black Amazonian characid pile to maneuver among freshwater reservoirs overgrown with underwater vegetation. Dorsal and anal fins are shifted to the back of the body. It lacks adipose fin.
Black Amazonian characid pike is a large fish: it reaches 2.5 m in length, and weighs up to 185 kg. It has large head with well-developed eyes and nostrils, but most of it is made up of jaws. Black Amazonian characid pike hunts “crocodile-style”: it makes a rush from an ambush, snaps its prey with its teeth and either drowns it if it has caught a waterfowl or a mammal, or simply swallows it whole if the prey is another fish or a large aquatic invertebrate. Its teeth are of a piercing type, so black Amazonian characid pike cannot tear prey to pieces, but can break its bones or shatter its shell with a strong bite. Despite the strength and power, black Amazonian characid pike has enemies itself; the most important among them is tyrannocharax, which is even larger and stronger than this fish, and can kill and swallow whole even an adult black Amazonian characid pike.
The fish is named for its characteristic coloration – a solid black or dark gray color; only the tips of its fins are contrastingly colored – they are bright red, especially in the spawning season. The brighter the red color on the fins, the healthier the fish. Due to this feature, fishes can establish a hierarchy without resorting to fights, in which they can get serious damage.
The spawning season of black Amazonian characid pike falls on May-June, when the flood season begins in South America. At this time, males and females of this species search for each other, their eggs and soft roe begin to ripe, and they utter piercing loud clicks under water with the help of jaws and gill covers. Females of this species are slightly larger than males, but the latter are more active and aggressive at the same time. They find females and swim around them, driving away rivals and waiting for the female to change her anger to mercy – black Amazonian characid pike is a solitary species and at first the female can express aggression even to the male during the mating season, so he behaves cautiously, giving the female the opportunity to get used to his presence. Spawning is preceded by courtship dances, during which the male presses against the female’s body from the side, accompanied by a series of clicks and trembling of the entire body for several seconds.
Eggs are spawned in portions 4-6 times a year, depending on the fatness of the female. A female of this species spawns from 5 to 10 thousand relatively large eggs at a time. During spawning, a pair of fishes plows a furrow in the soft bottom, spawns eggs in it and immediately buries them with lateral movements of their tails. The male patrols the clutch location for about a day, after which he swims away. Fry hatch after a few days. At first, they hunt benthic inhabitants. When the water level begins to drop, and underwater inhabitants often find themselves in natural traps, they turn to easy prey for the already grown-up fry of black Amazonian characid pike. Fry, in turn, also fall prey to larger fishes, but at this time, characid pike manages to avoid the main enemy of this species, tyrannocharax. Fry grow fast and double their size every 6 months until they reach at least two-thirds of adult size. However, many of them die in the first year and a half of their life – large turtles and predatory mammals also eat the young of black Amazonian characid pike.
Sexual maturity comes when fishes of this species reach the length of 1.4-1.5 m with an appropriate weight. Black Amazonian characid pike can live up to 40 years or a little more, but many fishes of this species die earlier before that.

This fish species was discovered by Bhut, the forum member.

Mole eel (Caecogymnotella psammotalpa)
Order: Cyprinoid fishes (Cypriniformes), suborder Knifefishes (Gymnotoidei)
Family: Electric eels (Electrophoridae)
Habitat: South America, basins of Amazon and Hyppolithe rivers.

Picture by Lambert

In northern part of South America vast river systems represent the home of various fishes. Some groups of fishes are endemic for South America, in particular, original gymnotid fishes. All of them are flesh-eating ones, and some use the electric discharge for hunting. However, the primary purpose of electric field of these fishes was the orientation in conditions where sight is useless – in muddy water, at night or in thickets of plants. One of gymnotid fish species during the evolution had completely reduced sight sense which appeared completely replaced by electric field in life of this fish.
At the bottom of South American rivers there are some species of digging fishes. Some of them eat mainly invertebrates, and others represent the active predators attacking smaller vertebrates – fishes and frogs. Largest of digging species of fishes is mole eel, blind species of electric eels adapted to life in top layer of river bottom. The body length of this fish reaches 1 meter; male is larger than female. The body of fish is lengthened, snake-like, similar to body of electric eel (Electrophorus electricus), its direct ancestor. But digging habit of life was substantially resulted in shape of mole eel. The anal fin of this species is underdeveloped; it represents only narrow edge along the bottom side of body, and does not take part in movement of fish, as at freely swimming gymnotids. Tips of fin rays jut out from fin plica and serve as a support when fish creeps through bottom sediments. Pigmentation of body is substantially lost: fish has pale colouring, and its skin has only slight pinkish-yellow shade. At young fishes skin is pale grey, and body is transparent. At adult fishes eyes had completely reduced, and there are only two dark spots under skin near to edges of mouth. At young fishes eyes are advanced much better; they are hidden under skin, but it is thin and transparent, therefore young fishes react to light, leaving from lightened places to darkness, and can distinguish the subjects contrasting with the general background. Young fishes live in thickets of plants and in shallow water, and are dug in sand only in case of danger though willingly creep in thickness of layer of fallen leaves covering bottom of rivers flowing in tropical forest. At the age of 1 year they pass to burrowing way of life and get shape of adult fishes, and at the third year of life they become able to breed.
The adult fish almost never leaves sand. It creeps in top layer of ground, coiling like snake. The tip of muzzle of mole eel is covered with very hard skin helping to carve its way in thickness of sand. Operculums of fish are supplied with leathery valves along the edge; it protects gills from contamination. However, this fish respires mainly with the help of skin (mole eel receives this way up to 60% of needed oxygen). At lack of oxygen or if the fish was dug deeply in ground, blood vessels of skin can dilate. Thus the body of fish gets visible pink color. If necessary, fish canrespire with the help of skin within several hours.
Mole eel orientates itself in surrounding world with the help of electric field. Creeping in ground, fish feels the changes of electric field connected to different electroconductivity of subjects (stones, live plants and driftwood). Mole eel defines the presence of other live beings nearby from it the same way. This fish has inherited from the ancestor the ability of generation of strong electric pulses. This skill is absolutely necessary for hunting and self-defense – fish stuns by discharges small fishes and crustaceans, and eats them. Also the strong electric pulse can paralyse or frighten off large predator hunting this fish.
Spawning of mole eel is not connected to the certain season. Male searches for the female ready to spawning, being guided by smell, and, having come nearer to her to safe distance, makes a series of weak electric pulses forming “the love message” to the female. If the female begins to answer male synchronously, the couple continues courting. By movements of forward part of body male and female dig a hole in which female spawns eggs (up to 500 eggs in the clutch). Male at once fertilizes them and then takes in mouth and broods during 4 – 5 days, cautiously pumping water through mouth. Larvae keep in male’s mouth within several days while yolk sac resolves at them. Young fishes lead active life in shallow water near the riverbanks, moving to deeper sites of river channel as they grow up. They also are predators, and eat small fishes and larvae of insects.

Rainbow silverscaler (Argentopleura iridescens)
Order: Cyprinoids (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: deep part of Fourseas.
Cyprinoids are mainly freshwater fishes, though separate representatives of order can live any time in sea water. And some freshwater species regularly come to sea water for feeding. Earlier such species of cyprinoids lived in Black, Caspian and Aral seas. And, when Fourseas had appeared in Neocene at the territory of Southern Europe, some species of cyprinid fishes survived during mass extinction, had mastered this new environment.
One of main pelagic species of Fourseas belongs to cyprinids. It is silverscaler, the descendant of roach (Rutilus rutilus). This fish appreciably differs from the ancestor, first of all by size and habit of life.
Silverscaler is schooling fish about one meter long, weighting about 15 kg. At it there are muscled body and wide two-lobed tail fin. It is a fish of silvery colouring with bluish shade and strong iridescent shine on sides. Back is appreciably darker than sides, and iridescent shine is swept less up on it. Back fin is short, high and transparent; on it there is a coal-black cross strip – with the help of this natural label fishes of present species distinguish congeners at the large distance. To be less appreciable for predators, fishes simply lower back fin, and become imperceptible on the background of blue water. The mouth is rather small, but it can extend forward as a tube. This fish is mainly zoophagous – it eats invertebrates and fry of fishes (primarily gobies). As at all cyprinids, at silverscaler there are no teeth, but on branchial arches sharp pharyngeal teeth permitting crushing of armors of crustaceans and to keep small fishes are advanced.
Silverscalers keep in huge schools numbering up to hundred of fishes and more. Schools usually include fishes of approximately equal size and age. The expressed leader is not present in them. The school synchronously moves in thickness of water, and scatters in sides as if dissolving in blue haze of water at approach of predator (for example, the tsarfish, the largest inhabitant of Fourseas). When danger is over, fishes gather, signaling to neighbours by movements of back fins.
The spawning of silverscalers takes place in the spring in reeds among thickets of pondweed and eel grass. Fertility of the adult female is up to 100 thousand eggs. The spawning proceeds very roughly: fishes jump out from water, plop down with loud splash; males in schools of four - five individuals chase females ready to spawning. In spawning season males have elements of spawning dress: on their operculums “pearl rash” appears, and the tail fin has red colouring. In spawning season fishes become easily excitable and any sharp burst results to their active jumping out from water in great number. Fishes prefer to spawn approximately in the beginning of spring while water plants only have started to grow, and water is cold and rich in oxygen. There is one more reason in it: in cold water appetite of predators is reduced, and the larvae will be in relatively safety.
Similarly to the majority of cyprinids, these fishes do not care of eggs, and the part of eggs may be had simply eaten by congeners.
The incubating lasts about two weeks. For this time the significant part of eggs is eaten by various animals. The larva hangs on plants two more days, and then turns to fry. Schools of fry of silverscaler leave the coastal zone and pass to life in high sea. To the age of five years fishes reach the length 50 – 60 cm and become sexual mature. Life expectancy at this species may be up to 35-40 years.

Whiteone (Squaspius squaspius)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: eastern Europe, large rivers.
Cyprinid fish rarely become specialized predators, as they have few adaptations to such a lifestyle. In particular, they lack teeth; and the few species that nevertheless master this way of life can only feed on prey much smaller than their own size. In the Neocene, large reservoirs of eastern Europe are inhabited by whiteone – a descendant of the chub (Squalius cephalus) – one of the species of carnivorous cyprinids. This is a large fish, reaching 1.5 m in length and 20 kg in weight.
This fish species inhabits coastal waters with areas of thickets of aquatic plants, and prefers to wait for prey, hiding among plants. Whiteone has an elongated, torpedo-shaped body, silvery scales with a golden sheen, and dark fins. Dorsal and anal fins are shifted to the posterior third of the body; their 2-3 anterior rays fuse together into a rigid, sedentary thorn that helps to keep the fin open. Tail fin is forked, with widely separated lobes; its edge rays from above and below also fuse into spines, serving mainly to increase the rigidity of the fin itself. The head is massive, flattened in shape, with a wide mouth, capable of stretching into a tube and sucking prey when opened. Large eyes with a red iris help to search for prey with the help of vision.
Whiteone is a predator feeding mainly on small fish; hunting is accompanied by characteristic powerful splashes noticeable on the surface of the water. Often during the hunt, the fish jumps out of the water following its prey. On occasion, these fishes willingly eat insects that have fallen into the water, as well as aquatic nymphs of mayflies, caddisflies and other species. In young fishes, a significant part of the diet consists of aquatic invertebrates.
Spawning occurs in the spring, after the flooding of rivers and the regrowth of aquatic plants. The male gets a characteristic courtship dress: the golden hue of the scales becomes more saturated; nuptial efflorescences of a multitude of epithelial tubercles appear on the head. Males share coastal areas with thickets of small-leaved aquatic plants into numerous individual territories, and claim them with vertical jumps out of the water. Sometimes tournaments take place between males, accompanied by loud clicking of pharyngeal teeth and jumping out of the water. Often a stronger male pushes rivals from his territory with snout blows. The female is larger than the male; her color pales during the spawning period, and her back and head turn black when ready to spawn. Spawning takes place in the thickets chosen by the male. Sometimes the male manages to fertilize the clutches of two females. He stays on his territory until the larvae hatch – for about 5-8 days, depending on the water temperature. The female leaves the clutch immediately after spawning, and the male may attack a female who is not ready to spawn if she appears near the clutch. Fertility reaches 200 thousand eggs. By the age of four, young fishes reach a length of 50 cm, and can take part in spawning, although they most often stay in less attractive areas of coastal thickets. Life expectancy reaches 50 years or more.

This fish species was discovered by Kazimir Adamovich, the forum member.

Everyfish (Ruliccus ruliccus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: eastern Europe, various freshwater reservoirs – stagnant and slow-flowing waters.
In the human era, hybrids of roach (Rutilus rutilus) with other cyprinid fishes – silver bream (Blicca bjoerkna) and bream (Abramis brama) – were known. In the conditions of the Ice Age, when these species were forced to share a very limited living space, such intergenerational hybrids began to appear much more often, and in some isolated reservoirs no purebred individuals remained at all, being replaces by them. Hybrids successfully coexisted with representatives of the original species, gradually separating into independent species. In the Neocene, everyfish, a descendant of such hybrids, lives in the rivers of Europe.
This fish species has preserved the “intermediate” features of ancestral species: the body is deeper than that of roach, but lower than that of bream and silver bream. The hump characteristic of the latter ones is kept in the front part of the body; the head is relatively small, with inferior mouth capable of stretching into a tube. The scales are silvery; the back is slightly darker. This fish species is relatively slow swimmer; fins are rounded and relatively short and wide. Pectoral fins are orange in color; abdiminal and anal ones are burgundy, especially during the spawning period. The eyes are large and red.
An adult individual reaches a length of 30 cm and a weight of up to 2.5 kg, but individuals weighing more than a kilogram are rare; they are found only in large rivers and lakes. Shallow rivers, lakes and swamps are inhabited by small individuals capable of withstanding a decrease in the oxygen content in the water.
According to the type of nutrition, this species is benthophagous; the basis of diet consists of small mollusks – bivalves and gastropods. Pharyngeal teeth are of crushing type and easily grind their shells.
This species is relatively cold-resistant and prefers to hide in cold pools during hot summer weeks. In autumn, fishes living in swamps and lakes are bury themselves in the bottom to a depth of up to half a meter, where they winter safely.
Spawning occurs early in spring, immediately after the ice melts, when the water is clean and rich in oxygen. The favorite substrate for spawning is the rotten remains of last year’s aquatic vegetation. The male digs a hole with his pelvic fins, and gives the female a signal to approach with the anal fin. At the same time, he utters loud squeaking sounds, rubbing his pharyngeal teeth against each other. Fertility is up to 30 thousand eggs. After spawning, fishes fill a hole in with the movements of their tails and swim away. Young fishes die in masses with a sharp drop in the water level in reservoirs, as well as during summer suffocations. Sexual maturity comes at the age of 3 years; life expectancy often reaches 40 years or more.

This fish species was discovered by Kazimir Adamovich, the forum member.

Ornate Pygmy Carp (Aureocyprinus ornatus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: Slow, moving, well sheltered creeks and waterways, including tributaries of the Murray River, in southern and south-eastern Meganesia.
The waterways of Holocene Australia suffered greatly from the introduction of invasive kinds of domestic and edible fish, the Goldfish was one such invader.
Some of its descendants in Neocene Meganesia include smaller, more ornate forms that resemble a partway between a fancy domestic goldfish, and wild carp such as Crucians.
The ornate pygmy carp is one such example, being about 15 centimeters in body length minus the tail. Its body is fairly deep, in order for predators to have trouble swallowing it, they retain the elongate, flowing fins of its domestic ancestor. They prefer weedy, sheltered waterways with a lot of refuge from predators. They can also inhabit partially stagnant water for extended periods of time. This fish a yellowy bronze colour, with some reddish sheen, and all of its fins are elongated, the male’s breeding colours on the fins are red with dark banding and occulated spots. The fins of the female are a shorter than those of the male, and are a dull red.
In diet it is much like a typical goldfish or crucian, feeding on small crustaceans, insect larva, small molluscs, worms and detritus. Unlike their ancestor, they are mostly solitary outside of the breeding season, and tend to be very shy, with the male’s breeding colours fading out of season. In the southern part of their range, they can survive low water temperature.
Breeding usually occurs based on water temperature and availability of resources, but spring or winter is the most common season for breeding. The female attaches her eggs to underwater plants, and the male fertilizes them, usually about 400 to 1000 are laid, which hatch within 60 hours. Lifespan is usually about 9 years.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

River crossbreed (Mixocarassius hybridogenus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: eastern Europe, freshwater reservoirs of various types.
In the XX century, many invasive Far Eastern fishes got to Eastern Europe, one of which was the Prussian carp (Carassius gibelio). It was notable for the fact that the development of its eggs could be stimulated by the soft roe of any cyprinid fish, so there were always more females in its populations, and in some ones, males there were none at all. During the Ice Age, it partially displaced, partially assimilated the local European crucian carp (Carassius carassius) and feral carp (Cyprinus carpio) populations. Hybrids were often unviable or infertile, but some combinations of genes turned out to be more successful than others and their owners survived. Some hybridogenic populations survived during the Ice Age at the turn of the Holocene and Neocene, turning to a separate cyprinid fish genus.
The Neocene descendant of crucian carp and common carp hybrids is the river crossbreed. This widespread fish forms two distinct ecological forms: semi-migratory one, living in the lower reaches of large rivers and spawning in floodplain reservoirs upstream, and sedentary one, permanently residing in floodplain lakes and oxbow lakes. The semi-migratory form looks like a Eurasian carp of human era and reaches its size, but has silvery scales; the head of this fish is smaller than that of Eurasian carp, and the body immediately behind the head rises like a hump. The sedentary form has a rounded deep body, similar to the ancestral crucian carp, and rarely reaches a mass of more than one kilogram. Body coloration of this form is greenish with a dark back; there are almost no males in its populations. According to the type of feeding, both forms are predominantly benthophagous.
This fish is a slow swimmer: it has a massive build, rounded fins and a short tail. River crossbreeds spend a significant part of their time in the thickets of plants, searching for food. They have small eyes and poor eyesight, but the lateral line organs are well developed. They lack wattles; the mouth is inferior and toothless, extendable into a tube. These fishes feed on mollusks, larvae of aquatic insects, as well as on plants. They often dig out the tubers of arrowheads and other marsh plants from the silt. Large individuals include more plant food in their diet; the young ones are mainly zoophagous. This species is social, gathering in schools of a dozen adult fishes or more. Young individuals gather in more numerous schools.
From carp, river crossbreed has inherited a relative thermophilicity: adult fishes easily tolerate wintering under ice, and can even bury themselves in silt, surviving the winter, but spawn exclusively in warm water in late spring or early summer. In cool years and in the northern part of the range, spawning begins in mid-summer. Males and females gather in schools of up to 20-25 fishes and arrange courtship games in the thickets of aquatic plants, accompanied by splashing and jumping out of the water. Each female spawns up to 50 thousand eggs, which are immediately fertilized by the male. Fish do not protect the eggs, and a significant part of the eggs and fry appears destroyed by predators, and even eaten by adult fishes of this species. Sexual maturity comes around the 4th year of life, and life expectancy can be over 50 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Cleaning moroco (Mircopseudorasbora micropseudorasbora)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: eastern Europe, large rivers of the Fourseas basin.
Human activity has led to an irreversible breaking of the boundaries between zoogeographic realms, and to the appearance of alien fauna representatives in various places of the Earth. After the mankind disappearance, many of them survived in new ranges, and began to develop new survival strategies in due course of evolution. Stone moroco (Pseudorasbora parva) – a small unpretentious Far Eastern fish – became one of numerous successful settlers in European reservoirs, where it spread, despite the measures taken to destroy it. Its descendants in new habitats are not as numerous as those of Gambusia or Chinese sleeper, but among them, there is a species that survives thanks to a peculiar life strategy.
One of its descendants, cleaning moroco, is one of the smallest freshwater fish in Europe – its length does not exceed 5 cm. This fish lives in schools in large rivers, where it stays near snags and bottom vegetation thickets. It can hardly give a predator a physical rebuff – it lacks poison, spikes and shell. In case of a predator’s attack, it can only escape or hide in a school of its relatives. However, the lifestyle itself provides these fishes with excellent protection.
Cleaning moroco has concluded a kind of “agreement” with the strongest predators of the rivers of Europe, since it feeds on ectoparasites, cleaning the bodies of large fishes – such as tsarfish (Pseudohuso cataphractus) or largemouth catfish (Silurus megachasmus) – from them. Also, these fishes are able to clean smaller fishes from parasites without lingering on their bodies for a long time. If there are wounds on the body of the fish, cleaning moroco can simultaneously pluck out tissue particles, which its ancestor did on occasion. By cleaning wounds from dirt and particles of dying tissues, this fish prevents the development of diseases in large long-lived fishes. For this purpose, cleaning morocco has a scraping terminal mouth with thick fleecy lips, which can stretch to a tube. The feeding fish keeps its body perpendicular to the skin of the “client” and scratches its skin or the surface of the wound with an open mouth. Also, these fishes eat zooplankton and eggs of other species – including those who are provided with their cleaning services.
The elongated body of this species has a torpedo-shaped shape and is laterally compressed. Body color is silvery with a bluish tinge; fins are transparent. Black stripe stretches along the side from the tip of the snout across the eye to the base of the tail fin. On the posterior edge of the dorsal fin, there is a black smear with silver edging – a “false eye” that distracts the predator from the head of the fish. Male and female have the same coloration. By the time of spawning, the male gets nuptial tubercles on its head, and the female’s belly turns rounded.
Spawning is portioned and takes place in late spring and early summer in “waves” of 3-4 cycles. The female spawns up to 1000 small eggs at a time, which develop for 7-9 days, depending on the water temperature. Fry often fall prey to adults, so they hide in shallow bays with well-warmed water and thickets of aquatic plants. By the end of summer, they grow to a length of 2 centimeters, and join schools of adult relatives. Sexual maturity comes the next year, and the total life expectancy does not exceed 3-4 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

European moroco (Neopseudorasbora europaea)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: Eastern Europe, freshwater reservoirs of various types.
In the historical era, people had carried out massive work on the acclimatization of Far Eastern commercial fishes in Europe. In addition to them, a small and extremely unpretentious fish, the stone moroco (Pseudorasbora parva), was unintentionally settled widely. In the new conditions, it quickly bres in great numbers, and superseded the local ichthyofauna in some places. It survived changes in the biosphere at the turn of Holocene and Neocene, and in Neocene, its descendant, the European moroco, occupies an ecological niche of a small schooling predator. Its ancestor willingly ate larvae, fish juveniles and eggs. It resembles its ancestor in appearance, but is larger than it, and reaches the size of a common dace (Leuciscus leuciscus) of the human epoch. The body is compressed laterally, with pointed unpaired fins. The head has a pointed snout; the mouth opens wide and stretches into a tube. The body color is greenish-blue with a silvery sheen on the sides; the back is dark. From the middle of the body to the base of the tail fin, a black stroke stretches, continuing on the tail fin. Other fins are translucent and colorless.
The fish is very unpretentious and lives in a variety of reservoirs – from small rivers with a fast current to stagnant oxbows. This species prefers to stay close to the coast above depths of no more than 2-3 meters, and enters the thickets of underwater plants. In large reservoirs, schools of this species number several dozen fish, in shallow rivers – only 6-7 individuals. Each school has its own smell, by which the fishes recognize each other. Unlike its ancestor, the European moroco is exclusively zophagous. It feeds on juvenile fish, which it hunts in schools, as well as soft-bodied invertebrates and fish eggs. These fishes are able to attack in schools the fishes guarding their eggs and jointly destroy their clutches. Schools of these fish often appear at the spawning grounds of cyprinid fishes, where they destroy a significant part of the eggs.
Spawning of this species occurs in groups, in early summer, at the full moon. Fishes splash out of the water, chase each other, and scatter eggs over the bottom, where they develop among rocks or plant debris. There are up to 2 thousand eggs in the clutch. Young fishes reach sexual maturity at the age of 2 years; life expectancy does not exceed 10 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Shishigan (Cephalosqualius lepidocephalus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: rivers and lakes of Europe.
Human activity and glaciation have had a significant impact on the freshwater ichthyofauna of Eurasia. They led to a significant fragmentation of the ranges of a number of fish species, which contributed to the accumulation of morphological and ecological differences in isolated populations with subsequent speciation. With the stabilization of natural conditions in the early Neocene, natural selection reinforced these differences, contributing to the isolation of new forms from each other. One European fish species – European chub (Squalius cephalus) – survived the human epoch due to its wide range and ecological flexibility. After the retreat of the glaciers, chub descendants settled again in the fresh waters of Europe. The largest of them is shishigan (named after the evil spirit of Slavic legends), a predatory fish up to 1.2 m long and weighing up to 16 kg. This species has a well-recognized appearance: it has a massive bulbous head with a wide toothless mouth. Pharyngeal teeth are pointed. Tail stalk is short and thick; tail fin is wide. An area of elongated thick scales develops above the eyes. The iris of the eye is lemon yellow. The general color of the body is changeable; gray-green and dirty-brown tones predominate, with small spots and vertical strokes of irregular shape. The belly is silver-gray. Dorsal, tail and pectoral fins are translucent; pelvic and anal fins are bright red. In large, strong males, white spots appear on the anal fin – perhaps they serve as a signal for females, stimulating them to spawn eggs.
Shishigan lives in lakes and rivers with a slow current, avoiding, however, swampy areas. Fish keeps off the coast, often patrolling the coastal waters along the edge of thickets of aquatic plants. It loses speed to pike, so it feeds on any slow-moving prey – arthropods, snails, wounded fish, shorebirds and waterfowl. Sometimes this fish ambushes at the watering hole, and even drags the cubs of forest harelopes. Competing for prey by the pike descendants, shishigan can catch smaller, as well as more secretive creatures, which decreases the rate of competition. In addition, it avoids settling in reservoirs with acidic peat water.
Spawning takes place in April-May, when the water is warmed up. At this time, males chase females by scent, poking them in bellies with long scales on their heads. If the female hits male with her head scales in the side, the male retreats, avoiding the conflict. Shishigans fight for territory and females with similar pokes, although usually the fight is preceded by a ritual displaying of the bright coloration of anal fin. Shishigan female spawns 13-17 thousand small and sticky eggs among plants. Sometimes they stick to the paws of waterfowl and are transferred to other reservoirs. Young shishigans hatch after 8-10 days. Young fishes often become prey to adult relatives, so the survival rate of offspring is low. They reach sexual maturity at 5 years old, with a weight of 3 kg. Life expectancy is over 20 years, although a significant part of fishes dies before reaching puberty.

This fish species was discovered by Nick, the forum member.

False barbel (Barbogobio pseudobarbus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitats: Europe, flowing oxygen-rich reservoirs with sandy or rocky bottoms.
Common barbel (Barbus barbus) lived in the rivers of Europe during the human era, but due to human activity its number decreased and it did not survive the ecological crisis. In Neocene, its niche was occupied by false barbel – its ecological analogue, which actually is a descendant of gudgeon (Gobio gobio). In due course of evolution, it has changed significantly compared to its ancestor: it is a fairly large fish, reaching a maximum length of up to 70 cm with a weight of about 8 kg. In reservoirs with a poor food supply, this species can produce dwarf forms; the length of such fish usually does not exceed 30 cm, and weight is up to 500 g. In its appearance, false barbel resembles its greatly enlarged ancestor. It has a flattened head and a cylindrical body with a strong tail. The mouth is inferior, equipped with a pair of sensitive fleshy wattles. Back is brown, darkening with age; sides are silvery, and there is a chain of black spots along the lateral line; the belly and the lower part of the head are white. The fins are transparent; the skin is covered with small scales and a layer of slime.
According to its feeding habits, this species is a benthophagous, feeding on insect larvae, worms, mollusks; it does not disdain fish eggs and fry. Unlike their ancestors, these fishes are strictly territorial, occupying areas along the riverbank, usually with thickets of plants or other shelters. Adults claim the territory, squeaking with their pharyngeal teeth. When a stranger appears on the territory, the conflict is usually reduced to the exchange of sound warnings, after which the trespasser swims away. In rare cases, fishes arrange a fight, accompanying it with sharp sounds.
False barbel lives in the foothills and river valleys, where the bottom is rocky or sandy, and the water temperature is usually low. Therefore, spawning in this species occurs in late spring or early summer, when the water warms up enough. A pair of fishes chooses a site with a constant calm current and a gravel bottom, in which the female buries its eggs. Adult fishes do not care about offspring, and can easily eat their own young. Fertility is up to 10-15 thousand large eggs developing in the thickness of the substrate for up to 10 days. The life expectancy reaches 20 years, in dwarf forms up to 15 years; the fish reaches sexual maturity at the age of 3-5 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Ooze barbel (Pelobarbus cryptus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: north of Zinj Land, temporary reservoirs.
A significant part of the East African microcontinent, also known as Zinj Land, represents an arid area with a small number of permanent freshwater reservoirs. A significant part of the reservoirs represents temporary rivers and drying lakes. However, they are also inhabited by fishes, which in the process of evolution have developed the ability to survive drought. A significant part of small fish is present by annual species whose eggs survive drought, and adults die. Also, in the arid regions of the microcontinent, there are several fish species that can survive drought in adulthood. One of them is ooze barbel belonging to a diverse group of cyprinid fishes.
This barbel is an ecological analogue of the tench (Tinca tinca) in swampy African lakes. The length of adults is up to 50 cm. Body is elongated, not deep, of almost cylindrical shape. Head is massive, with a blunted snout and inferior mouth. Eyes are large, with a golden iris. Fins are rounded – it is a slow–swimming type of fish. Body color is golden-green with a wide black band at the base of the tail fin. Fins are translucent, of grayish shade.
This fish has an inferior crescent-shaped mouth of a scraping type with a slightly keratinized lower lip – this fish is convergently similar to representatives of the genus Labeo, differing from them in its undemanding oxygen content in water. Thus, ooze barbel avoids competition with Labeo fishes, populating reservoirs where these fish cannot live. Like Labeo, it feeds on blue-green and filamentous algae, which grow rapidly in shallow waters in bright sunlight. When feeding, ooze barbel scrapes off the top layer of silt along with algae, and passes it through the intestines, extracting organic matter and digesting numerous protozoans and bacteria that multiply in the silt.
Reproduction takes place at the beginning of the rain season, when reservoirs are filled with clean and oxygen-rich rainwater. Ready–to-breed fishes quickly gather in schools and spawn eggs – up to 100 thousand eggs from one female. Fish do not protect eggs, and a significant part of them dies. Fry of this species are characterized by a high growth rate – they consume a large amount of protein feed, and manage to eat part of the eggs from late spawned fish. They also eat branchiopod crustaceans and aquatic insects. By the end of the wet season, the young fish reaches a length of 6-7 cm.
When the reservoir dries up, ooze barbel buries itself in the ground to a depth of up to one meter. The fish burrows, making a spiral tunnel in the wet ground with its muzzle. Often young fishes use the tunnels of adult individuals, surviving successfully without extra effort. In the ground, the fish is covered with abundant viscous slime, which glues the soil into a kind of cocoon, leaving only a hole at the mouth. It falls into a dormant condition, and oxygen consumption is greatly reduced. When the ground gets wet, the fish carefully tunnels to the surface without leaving the shelter immediately – sometimes heavy rains fill the basins of reservoirs, but the water dries out quickly. Usually, most fishes come out of their dormancy only with the onset of stable rainy weather.
Sexual maturity of young fishes comes at the age of 4 years; life expectancy reaches 20 years.

Potamolabeo (Potamolabeo platycephalus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: Zinj Land, fast-flowing mountain rivers and streams.
Zinj Land had separated from Africa by break line marked even in prehistoric time by Great Rift Valley. This enormous land mass, separated from the main continent, includes territories on which in human epoch eastern part of Ethiopia, Somalia, Kenya, Tanzania and the north of Mozambique were placed. In human epoch it was the district including mountainous areas and savanna with additions of woods. Having separated from the continent, Zinj Land had carried away Kilimanjaro, the highest mountain of continent. Rivers of this huge island are short, but flow in warm district favorable to development of diverse life forms. Because of isolation rivers of island are rich in endemic species of fishes. Many interesting species of fishes live in cool mountain rivers. One of these species shows excellent fitness to life in rough current. It is potamolabeo, “stream labeo”, the descendant of cyprinid fishes of genus Labeo, lived in African rivers in Holocene.
Potamolabeo is rather large fish: length of adult individual is up to 30 cm. At this fish sexual dimorphism is well expressed – it is the unusual phenomenon in cyprinid family. The female is larger than male, but at the male head is relatively bigger. Also on operculums of the male the several lines of small spikes increasing in courtship season grow.
Potamolabeo looks very clumsily: the fish seems made of two parts of completely different fishes. At this fish there are massive flat head, slightly convex eyes and constantly opened mouth looking like sucker. On lips of fish some numbers of corneous denticles develop – similarly to all cyprinids, potamolabeo has no true teeth. Operculums of this fish are shifted downwards, and gills are protected from below from sand by additional skin valves.
Body of fish is thin and low. Wide pectoral fins serve potamolabeo as rudders of depth. This fish lives in fast flowing water; therefore, having slightly turned fins, it can emerge or nestle against the bottom easily, not spending superfluous efforts. The first ray of pectoral and abdominal fins at fishes of both sexes is thick, strong, and saw-like jagged, having a spike on the tip. At males spike is thicker, rather than at females.
Back fin of potamolabeo is very bright – red with black speckles. Its basis is short, and fin rays are long. This fin has the function of warning signal, equally important both for the male, and for the female. Therefore back fin is equally bright at representatives of both sexes.
Strong current is a factor of environment difficult to struggle with it. In current fishes develop two basic tactics of behaviour: they either become fast swimmers to move against the stream, staying on place, or avoid the current. Potamolabeo had chosen the second way: this massive fish swims hardly and does not emerge without special necessities. All efforts of fish are directed on being kept at the bottom and to not be carried away by rough current. This fish keeps by spikes of fins for stones, and the counter stream presses fish to stones. Swimming bladder at potamolabeo is lack.
This fish keeps on stony areas of rivers. Potamolabeo eats algae, water mosses and larvae of insects attaching to stones. Also it can clean off microscopic seaweed growing on leaves of underwater plants living in flowing water. Except for corneous denticles, on bottom jaw the corneous edges develop, assisting to scrape off algae. For digestion of such poorly nutritious food at fish the long intestines had developed – its length fifteen times exceeds length of fish body. Being filled with food, intestines also raise density of fish and facilitate resistance to current.
Feeding by so specific kind of forage had caused the certain changes in habit of life of potamolabeo. Potamolabeo is territorial and aggressive. Each fish has territory the area about 10 square meters; the fish knows borders of territory and furiously protects them from neighbours. Bushes of plants and large stones serve as boundary marks. If the stranger interferes in limits of territory of fish, the owner of territory quickly lifts and lowers back fin some times. It is a signal, that the stranger is noticed, and simultaneously it is the requirement to leave the territory which is already occupied. If the stranger does not leave territory, the fish owning a site, swims towards to the contender, having opened back fin. This is the warning of opportunity to fight. Fights at potamolabeo are very severe: fish accelerates speed and puts to the opponent ramming impacts by a head. Such impact, if it is put to the operculum area, may even kill the contender. There is one more, more harmless reception of struggle – the fish picks up the opponent by head, lifts it above the bottom and by strong impact of snout throws upwards. Current picks up the infringer of territory and carries it to some distance from the site occupied by with a fish.
In spawning season male leaves its territory and spawns with the female in her territory. As a rule, the male chooses the female living in the neighbourhood. Courtship at these fishes is simple and even a little bit formal: the male simply drives the female, trying to swim forward and to touch its head by spikes growing on operculums. Accepting the courting, the female trembles by pectoral fins and presses back fin to the back. Pair of fishes simply scatters eggs at the bottom and does not care of them. For one spawning the pair spawns more than 200 thousands eggs. Eggs fail between stones and are incubating in conditions of good supply by oxygen till about two weeks. The first some minutes after fertilization the shell of eggs is not sticky, but further it swells and on its surface slime appears, which pastes eggs to stones and driftwood. Larvae of potamolabeo are inactive. They hide in cracks between stones and eat bacterial slime and particles of organic substances. Larger fry keep secretively under stones or in bushes of water plants. Young fishes migrate in shallow streams where there are no adult fishes, and gradually grow there. At this stage of life many fishes become victims of various water predators. As they grow, they settle in deeper sites of river channel and occupy individual sites. Young fishes take part in spawning at one-year-old age.

Cleaning nanolabeo (Nanolabeo hygeius)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: Africa, rivers and lakes of Congo basin.
In due course of evolution, many species of living beings independently of each other developed similar tactics of survival due to the benefits brought to the surrounding species. Thanks to such an unspoken “non-aggression pact”, representatives of such species can not be afraid of predation by many dangerous species living in the neighborhood.
The forests of Central Africa remained largely untouched during the human era due to the inaccessibility of these areas and the unhealthy climate, which prevented the expansion of human activity. In this part of the continent, a large number of swamps and small rivers have been preserved, which have become a kind of refuge for freshwater fish of this continent. In Neocene, this area became a place of fish settlement to the recovering ecosystems of the continent.
Among the freshwater fishes of Central Africa, there is a species whose well-being depends entirely on the diversity and density of the settlement of fishes of other species. This species is remarkable in a very catchy appearance, which is the key to its well-being. A very small cyprinid fish, cleaning nanolabeo, provides cleaning services to large fish, receiving a safe life in return. Body length of this species is up to 5 cm. Body is thin and elongated, with wide pectoral and pelvic fins. Dorsal and tail fins are small and rounded. On the underside of the paired fins, there are small bristles that help this fish attach to the bodies of other fishes during their cleaning.
All fins are transparent, with a grayish tinge. Body, on the contrary, is colored very catchy. Back is velvety black; belly is creamy white, and along each side a wide, sometimes intermittent “neon” stripe with a bright blue sheen stretches, being clearly visible even in low light.
Mouth of cleaning nanolabeo is transformed into a suction cup, which can turn up, forward and down with equal ease.
These fishes settle near well-visible details of the landscape – stones, snags, trunks and roots of trees, choosing places where there is shelter. This species settles in a school numbering 2-3 males and 3-4 females. Usually these fishes keep in the rays of light penetrating through the forest canopy, and the “neon” stripes glow brightly, making them clearly visible to the surrounding fishes coming for sanitary treatment.
The food of cleaning nanolabeo consists almost exclusively of what this fish finds on bodies of other fishes that come for cleaning. Parasitic crustaceans and their egg sacs, small leeches, helminths settling on the gills, as well as dying tissues at the edges of wounds are the usual diet of this species. If this food is not enough, fish can gather sedentary and slow-moving invertebrates from rocks and driftwood. Any fish that has come for treatment is cleaned immediately by all fishes of the school that settles at the “sanitary treatment point”. Some small fishes come for cleaning in whole schools, and in this case “customers” are only slightly larger than the cleaner itself.
All the fishes in the school are well acquainted with each other and carefully guard their territory from strangers. The more food has fish, the less tense the relationship in the group. In this case, a solitary fish has the opportunity to stick to the school, observing the necessary caution and showing signs of submission (first of all, “extinguishing” its neon strips on the sides). If there is a lack of food in the school, conflicts can break out, which end with the expulsion of one of fishes.
Spawning of cleaning nanolabeo takes place in school; males spawn in turns with each of the females over the bottom, scattering fertilized eggs among rotting foliage and debris. Fishes do not guard the clutch. Spawning is preceded by intense mating games, when partners chase each other in the rays of light, flashing neon stripes, which at this moment become wider. The female, ready to spawn, rushes to the bottom and fades – the neon strip turns black. Males chasing her also darken and a group of fishes quickly spawns their eggs over the bottom. After spawning, fishes hide in the thickets, and their color is gradually restored to bright one.
Incubation of eggs lasts about a day. A day later, the larvae turn into fry and begin to swim. They stay near the bottom, hiding among aquatic plants. Young fishes do not have shining stripes, which appear only by the age of 4 months. At the same time, the young fish reaches sexual maturity. Of young fishes, schools of approximately the same age form, and some fishes enter schools of adults.

Mudsleeper (Dormicyprinus robustus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: Meganesia, savanna areas to the west from Eyre Gulf; temporary reservoirs.

Picture by Carlos Pizcueta (Electreel)

Not all species of animals and plants introduced by people to various places of the Earth had died out during global ecological crisis at the boundary of Holocene and Neocene. At various continents in Neocene flora and fauna it is possible to meet species descended from species introduced to these regions by people millions years ago. Ecosystems of islands and Australia, continent, for long time being in isolation, suffered from introducing of alien species especially strongly. In Neocene at the territory of Meganesia (continent united Australia and New Guinea) many species being descendants of non-native species live. In ichthyofauna of Meganesia one of their representatives is the large cyprinoid fish named mudsleeper. It is the descendant of of carp (Cyprinus carpio) introduced by people, which had exellently adapted to extreme conditions of new motherland.
Freshwater reservoirs in Meganesia are concentrated at the north and at the east, along Great Dividing Ridge. Farther at the west there is wide brackish-water Eyre Gulf; from the west only temporary rivers which may dry up completely for some months run into this gulf. In such reservoirs this fish is dominant species of ichthyofauna.
Body length of mudsleeper is about 40 cm. Body of this fish is prolonged; head is flattened and rather small. The fin shape of this species is characteristic for slowly swimming omnivorous cyprinids – all its fins are rounded and have soft rays. Only in back fin some forward rays have grown together to one strong prickle on which front edge small denticles develop. Colouring of body of mudsleeper is beautiful: there is golden-brown background with vertical greenish-black strips, one of which stretches across the eye. Fins are transparent with reddish-orange shade.
This fish species is omnivorous, and equally willingly eats insects, aquatic vegetation and even dead animals had sunk during rains.
The remarkable skill of its ancestor, the ability to go through temporary drying of reservoir, had received the further development at this species. Mudsleeper can survive till about 15 months, having dug in ground of the dried up reservoir to the depth of about one meter. At this time in organism of fish significant physiological changes proceed. Shortly before complete drying of reservoir muscles of fish as if impregnate with water and become slightly watery. It is the stock of water necessary for successful surviving in drought. When water level falls so, that it does not provide the survival of fish, it starts to dig in ground the vertical shaft to the depth up to one meter. Usually the individuals living in droughter conditions hide deeper, than ones from populations of the coast of Eyre Gulf. Having reached the needed depth, fish forms the small chamber, in which falls into anabiosis, by movements of body. In chamber fish is turned as a ring, having covered operculums by tail fin from below. The body of fish starts to produce slime plentifully. Thus water is gradually “squeezed out” of muscles. Slime is produced in small amount up to the end of term of anabiosis, therefore to the end of dry season fish seems dried alive. At this time fish grows thin strongly; even its eyes fall in, but blood in any case is kept liquid. During anabiosis the body is covered with “cocoon” in which there is only one small aperture which opens to the mouth. External surface of cocoon represents the hardened crust of sand and clay stuck to strong cover by protein fractions of slime. During the rain when the ground is impregnated with water enough, the cocoon becomes soggy quickly, and fish absorbs water through skin of stomach and gills. When muscles restore approximately 50% of the lost moisture, fish starts to get out of ground captivity.
Right after filling of reservoirs by water mudsleepers arrange noisy courtship games. In day time they are slow and hide among quickly growing plants, but in the evening males one by one or in small groups jump from water and loudly splash back, involving females. At night males start to chase females and to drive them to thickets of underwater plants. Nestling to females, males force them to spawn eggs. Fertility of these fishes makes over 50 thousand eggs.
At the majority of cyprinoid fishes the care of posterity is limited only by spawning of plenty of eggs in place favorable for its incubation. Mudsleeper had not departed this “tradition”. The young ones hatch after 3 – 4 days and start to develop very quickly. Young fishes are mainly zoophagous - they had to grow up as much as possible while the reservoir is not dried up. They eat larvae of insects, small crustaceans (their eggs go through drought in dried up silt), and larger ones devour their own congeners. Having such diet some individuals grow to the length of 13 – 15 cm to the time of drying of reservoir. At such size they have a great chance to survive in drought in anabiosis. Small individuals also have chance to survive: many of them successfully live the first years of life in not drying up ponds in lower reaches of rivers. These fishes do not endure salt water and do not live in Eyre Gulf.
At the third year of life mudsleeper reaches a sexual maturity. Life expectancy of this species may reach 40 years and more – ageing of a fish is sharply slowed down while it falls into anabiosis.

Burrowing fish (Cryptotinca subterranea)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: areas of Central Asia with a seasonal climate and drying reservoirs – to the east of Fourseas.
The central regions of Eurasia in Neocene epoch are still quite a harsh place to live. The huge brackish basin of Fourseas supports life in this area, and the mountain ranges of Central Asia serve as collectors of water vapor in the form of snow falling on their peaks. In spring, the snow begins to melt and mountain rivers overflow with water, turning into muddy streams. They rush to the shores of Fourseas, but it is not easy to reach it. Rivers flowing into Fourseas from the east do not always reach the sea. Most often they spill into vast shallow deltas, form wetlands and disappear among the sands. By the beginning of autumn, the sun dries them, and by winter, only dry riverbeds with some dirty puddles in place of deep pools remain from such rivers. In such conditions, it is extremely difficult for fish to survive, but still such temporary reservoirs are inhabited by fishes that have adapted to such conditions.
The sun illuminates and warms up shallow waters well, contributing to the development of fast-growing filamentous algae. This food source is used by a special herbivorous fish species found in temporary reservoirs of Central Asia – burrowing fish.
This fish species is a descendant of tench (Tinca tinca), one of the common fishes in the rivers of Eurasia. The ability of tench to survive the drying out of reservoirs, burrowing into the ground, helped it survive and populate such unfavorable for fish life places. It is a “sleeping” fish, which simply buries itself in the ground to a depth of 1 meter with the help of a muscular tail when the reservoir dries up. At the bottom of the vertical mine hole, due to the small evaporation area, water is stored for a long time, allowing this fish to live normally; the fish stays in the hole with its head up. When the remaining water evaporates and is absorbed into the ground, burrowing fish forms a protective capsule of mud and slime around itself by “tossing” inside the burrow. A layer of dense jelly-like slime forms between the capsule wall and the body of the fish, preventing the evaporation of water. Only a small gap at the top of the capsule, in front of the mouth of the fish, connects it with the environment.
Burrowing fish differs from its ancestor by an elongated cylindrical body; the length of an adult individual can reach 55-60 cm. Dorsal and anal fins are short, and tail fin is rounded and has rigid rays. It serves not only as a movement organ, but also as a shovel during the preparation for waiting out the drought. Fish has a large head with small eyes and a wide inferior mouth. Lips are covered with numerous corneous bristles and serve to scrape filamentous algae and films of unicellular algae from the substrate. Body lacks scales and is covered with abundant slime. The color of fish is bronze-green with a golden glow on the sides.
In the spring, when the reservoirs are filled with water, fishes leave their shelters and begin to prepare for the breeding season. During the “dry” wintering, reproductive products ripen in fishes, and fresh clean water stimulates mating behavior. These fishes spawn eggs on last year’s flooded vegetation. Spawning is accompanied by violent courtship games, during which the male drives the female through shallow water and pushes her towards the substrate for spawning eggs. At this time, the coloration of the male becomes bright green, and the back turns black. At this time, a large number of outgrowths (nuptial tubercles) appear on the head and operculi of the male.
Numerous eggs (up to 200 thousand ones from one female) develop without parental care for a week. Fry feed on a variety of infusoria and microscopic green algae. At any stage of development, burrowing fish is very resistant to lack of oxygen. Adults often emerge to the surface of the water and pass a jet of a mixture of water and air through the gills with effort. At the same time, a characteristic clicking sound is heard, and the upper layers of water are enriched with oxygen, which contributes to the normal life of other inhabitants of reservoirs. By the end of summer, the juveniles reach a length of about 2 cm. The first wintering is critically important for young burrowing fish. Most often, young fishes, not having the physical ability to dig a hole of sufficient depth, winter in pools where water remains during the winter. Less often, a young fish climbs into the burrow of an adult one and forms its own protective cocoon there. In the second year of life, young fishes already can winter alone successfully. They reach sexual maturity in the third year of life, and their life expectancy reaches 20 years.

Rainbow salmocyprinus (Salmocyprinus irideus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Cyprinids (Cyprinidae)
Habitat: India, upper courses of rivers flowing down from southern slopes of Himalayas.
Significant amount of small species of freshwater fishes had rather successfully endured the epoch of human domination. Destruction of habitats had resulted in extinction of some local endemic species, but in several hundreds thousand years they had been replaced with descendants of survived species. And some descendants of small fishes began to grow up promptly. This process had beem promoted by the emptying of ecological niches caused by overfishing of large fishes and destruction of their habitats. Among large species of fishes of Hindustan the schooling fish length up to 50 cm is especially remarkable; its sides shine in all colors of rainbow with obvious prevalence of lilac and violet. It is rainbow salmocyprinus, the descendant of rose danio (Brachydanio roseus), the species widely distributed in human epoch as aquarium fish.
The descendant of this species is changed in great degree. The fish has considerably increased in size compared to tiny ancestor, but has kept adherence to schooling way of life. Schools of salmocyprinus total up to one hundred individuals, and during the spawning season they gather to many thousands shoals. Body of salmocyprinus is muscled, slender, with short head and unpaired fins shifted to back part of body. This fish has superior mouth, pushing forward and upwards like a short tube. In corners of mouth two long mobile wattles grow. At night when the fish sleeps, wattles are turned forward and serve for the notification about approach of danger – a plenty of chemoreceptors and the cells feeling movement of water is located on them.
The body of these fishes is coloured very attractively. Sides have metal shine, and back is dark grey and matte. Colouring of sides is pinkish-lilac with blue and greenish shade. Beyond the spawning season male does not differ from the female in colouring. The female is little bit larger, rather than male, and her stomach is fuller. In courtship season male changes colouring to more sated one – sides turn rich pink, the top parts of sides are lilac turning to violet colouring of back. Fins at fishes of both sexes are transparent with bluish shine.
This fish eats food which may be gathered from surface of water – larvae of insects and other invertebrates living among floating plants, and also duckweed rich in proteins.
The ancestor of this species, rose danio, willingly spawned in fast flowing water. At salmocyprinus this feature of behaviour has received the further development: this species spawns in fast current in cool mountain rivers, as a salmon (hence the generic name, meaning “salmon – carp”). In spring, when in Himalayas snow thawing begins, the mountain rivers turn to rough streams. Feeling changes in chemical composition of water, schools of these fishes gather to many thousands shoals. Males get bright iridescent colouring but keep in common with females in united schools yet. Spawning places of this species represent thickets of small-leaved hydrophytes in upper courses of rivers at the shoaliness. Fishes swim upstream, overcoming small falls with strong jumps.
At the spawning places schools broke to small groups including about ten of fishes - approximately fifty-fifty males and females. Spawning begins in the morning. Males drive females in thickets of underwater plants and fertilize spawned eggs. By several movements of tail fishes straighten plants trampled down during the act of spawning, and leave thickets, giving up the place to new groups. After spawning fishes hide in deep holes and among large stones, in places protected from predators. Having had a rest after spawning, fishes move to middle watercourse. As against the majority of salmons, salmocyprinus can spawn many times repeatedly.
Fertility of one female makes up to 100000 small transparent eggs. Approximately in one week from them transparent larvae hatch. The first days of life larvae do not eat: yolk sac resolves at them. Having turned to fry they continue life in thickets of plants, eating microscopic aquatic animals. Fry gradually migrate downstream. At the age of 4 months, at length of 5 – 6 cm young fishes get pinkish shade on scales. At this time they gather to numerous shoals, numbering tens thousand individuals, and eat planktonic crustaceans. As they grow, their mouth from terminal becomes superior one, and at the age of about one year fishes pass to diet of adult individuals.
Rainbow salmocyprinus reaches sexual maturity at the age of 3 – 4 years. In upper courses of rivers this species frequently forms smaller slow-growing form spawning together with fishes of the normal size. Lifespan of these fishes makes about 20 years.

Murray Serpent Loach (Megalomisgurnus durophagus)
Order Cyprinoid fishes (Cypriniformes)
Family: Loaches (Cobitidae)
Habitat: The waterways of the Murray River, including montane waterways of the Great Dividing Range, absent in brackish waters nearing Eyre Gulf.
Apart from a few notable examples, Australian native fish have suffered since the end of the Holocene, with many introduced forms competing with them.
One such introduction was the Pond Loach (Misgurnus anguillicaudatus); this fish left numerous descendants in Neocene Meganesia. One of them is the Murray Serpent Loach, a form reaching up to a meter long, and being very slender, serpentine in appearance.
The head and eyes generally resemble its ancestor, having long sensory barbels, but the mouth is slightly wider, with a hardened palate and strong jaws adapted for crushing. Its body is very long and thin, more so than an eel, soft dorsal fin is short and rounded, caudal fin is rounded and extends partway up the back to aid it when it buries itself. These fish are mostly solitary, and feed predominately on snails, though they will also eat worms and small crustaceans. Body colour is a dark muddy brown with a pale yellow underside.
This fish will generally hide in the riverbed sediment when not hunting for food; it can also breathe air and resist desiccation, being able to cross between bodies of water overland. Breeding occurs by spawning when there is a higher flow rate of water in the winter; the male wraps around the female and stimulates her to release a cloud of up to 1500 eggs, which are then fertilized. The eggs hatch after about three days. Lifespan of this fish is up to 15 years.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Catfish loach (Barbatilurus barbatilurus)
Order: Cyprinoid fishes (Cypriniformes)
Family: Stone loaches (Nemacheilidae)
Habitat: Eastern Europe, rivers, large lakes; areas of a reservoir with a sandy bottom.
In the human era, the niche of a non-specialized predator and scavenger of reservoirs in eastern Europe was occupied by burbot (Lota lota). In Neocene, the climate of these areas is too warm for burbot and its niche is occupied by other species. One of them is catfish loach, a descendant of stone loach (Barbatula barbatula). In the human era, the loaches suffered greatly due to water pollution, and were preserved only in a few places in Eurasia. After the disappearance of mankind, their range shifted to the south along with the glacier.
This medium-sized fish (length up to half a meter, weight up to 1 kg) looks more like a small catfish than its ancestor. It has a large head with an impressive, though toothless mouth, small eyes in the upper part of the head, and well-developed wattles surrounding its mouth. This species has a very advanced chemical sense – the skin is scaleless, covered with a whole network of sensitive cells capable of perceiving chemicals dissolved in water. These cells are especially numerous on the wattles.
The cylindrical body is of a massive build, and powerful tail stalk indicates the benthic lifestyle of this species. Catfish loaches do not swim up into the water column, and prefer to stay on soft ground or among thickets of underwater plants. Tail fin is fan-shaped with a shallow notch on the posterior edge.
The color of the skin is mottled – darker marble vertical stripes on a greenish background. In some individuals, the stripes are almost not expressed, and the body has a uniform mottled color. Catfish loach is a bottom-dwelling inactive fish leading a predominantly nocturnal lifestyle and feeding on carrion, benthic organisms and eggs; it is able to catch a careless fish. During the day, the fish often buries itself in the ground, and only the upper part of the head and back remain on the surface. At this time, the fish breathes only through the silts in the upper part of its operculi. Due to its muscular body and tail, this fish is able to dig into the ground almost instantly in case of danger, and even crawl in the ground for a while, fleeing from chasing.
Spawning in this species begins in early spring, when the water is clean, fresh and rich in oxygen. Spawning takes place in pairs. At night, the male leaves the shelter, and finds a female ready for reproduction by the chemicals she emits. Courting her, male gets an almost black color with some light spots on the sides. If the female is ready to breed, the pair of fishes swims together for a while, and spawning begins in the early morning. These fishes bury their eggs in the ground, where they are reliably protected from enemies. Right during the spawning, a pair of fishes buries themselves almost entirely in the ground – usually only dorsal fins of fishes remain on the surface; occasionally they bury themselves entirely. A couple of fishes crawls side by side in the ground, spawns and fertilizes eggs, and buries them with movements of their tails. After spawning out all the eggs, fishes leave the spawning site, and no longer care about their offspring. Fertility is up to 3-4 thousand eggs.
Incubation lasts up to 2 weeks. Young fishes creep out from the thickness of the ground and hide in thickets of plants or among bottom debris. As young fishes grow, they occupy individual territories and protect them from their relatives. Sexual maturity comes at the age of 3-4 years; life expectancy reaches 20 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Long-termed archontobranchius (Archontobranchius longaevus)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Nothobranchiids (Nothobranchiidae)
Habitat: north of Zinj Land, shallow rivers and lakes.

Picture by Lyagushka

For tropical zone of the Earth so-called “annual” fishes are very characteristic. It is the large group of small species of cyprinodontiform fishes living till only one season, and surviving in drought as dormant eggs. In Old and New World there was a set of species of these fishes. Sometimes they could be met even in pools, existing only few weeks in rain season. The part of species of “annual” fishes had successfully gone through climatic changes of the boundary of Neocene and Holocene. In Neocene the active speciation of this group connected to expansion of area of tropical climate and split of African continent began. One species had gone on the unusual way of evolution - it turned to “perennial” species again, and had considerably increased in size. The ancestor of this fish belonged to number of small fishes of genus Notobranchius. Its descendant looks hereby Methuselah in comparison with ancestral forms: duration of its life makes about 15 years. For this feature the fish is named archontobranchius.
Archontobranchius lives in rivers of northern part of Zinj Land having slow current, strongly overgrown with water plants and well warmed by sun. It is a solitary fish aggressive to congeners out of spawning season.
The length of body of archontobranchius reaches 30 – 35 cm. This fish is a little similar to the goby: at archontobranchius there is massive body slightly compressed from sides, and large head with wide mouth turned upwards. Unpaired fins are rounded and shifted to back half of body. Tail fin is two-lobed, with small cut at back edge. Pectoral fins of males are wide and fan-shaped. The body of fish is covered with very small scales.
At archontobranchius the sexual dimorphism in size and colouring of body is well expressed. The male is larger and more aggressive, than the female, and it is painted much brighter, than the female. The back of fishes of both sexes is brown with black speckles – fish is less appreciable so for air predators. At male sides are blue with slanting faltering red strips. Eyes of male are bright blue and shining. On its pectoral fins there is a pattern of small black spots on red background, forming faltering cross lines.
Female is colored more modest, rather than male – at it there is “marble” brown colouring with grayish-green irregular-shaped spots; eyes are grey with slight shine. In populations the number of males is less, than the number of females – the significant part of males perishes because of bright colouring in beaks of fish-eating birds.
Archontobranchius is carnivorous fish; its food is made by water insects and their larvae, and also shrimps and fry of fishes. This fish hunts catch, which keeps near the surface of water.
The spawning of this fish passes very originally: in it features, characteristic for ancestors of archontobranchius were kept and had received the surprising continuation. This fish breeds at flood of the rivers, during the peak of rain season. Archontobranchiuses spawn in pairs, digging eggs in silt in shallow water. Fishes spawn in the morning, while fish-eating birds have not woken up yet. At this time shallow water literally boil from pairs of spawning fishes which hasten to lay eggs while sun is not rose high enough. Spawning pair jumps out from depth of reservoir to the shallow water, and is literally twisted in layer of coastal mud. At this moment male covers the female by the body, snapping her by pectoral fin or operculum. The female digs out in silt the furrow by sharp movements of head and breast and immediately lays in it small eggs (in clutch it may be up to 500 eggs). The male on the spot fertilizes eggs, and pair of fishes, spinning in silt, buries eggs. For one act of spawning fishes make in mud some furrows and lay in them all caviar which is produced by female. After spawning adult fishes slip from shallow water and swim out to depth. They hide under floating leaves of water plants and restore forces after tiresome spawning. The female spawns only once for a rain season; and one male can repeat spawning with different females some times having breaks approximately in two days. Right after spawning fishes feed more actively, and at females the forming of new portion of eggs begins, but its development stops up to new rain season. Rain water serves as stimulus for the further egg ripening.
Eggs of archontobranchius are small, but the period of their incubating stretches almost to one year. Conditions of egg incubating of This fish species are original: in some days after spawning shallows dry up, and eggs appears in layer of liquid mud, or even simply on land. It does not kill them: egg of this fish easily tolerates drying due to dense shell. This feature inherited from ancestors, allows archontobranchius to settle actively. Eggs can be transferred in dry season by wind or on legs of animals to long distances. Sometimes water birds carry eggs on paws over sea passages, and archontobranchiuses may be met even at Madagascar, in Arabia and at the African coast of Tanganyica Passage. But there constant populations of this fish are not formed – practically all immigrants fall victims of local species of fishes and fish-eating birds. But in conditions of seasonal climate at the north of Zinj Land, when the rain season is replaced by drought, archontobranchius is out of competition.
Adult archontobranchiuses live in rivers and lakes which in drought may turn to stinking ponds with dirty water. These fishes are steady against lack of oxygen dissolved in water. They can respire, grasping an air bubble from the surface of water. When the fish holds air bubble in mouth, oxygen from it gets in blood through gills. When the reservoir dries up strongly, archontobranchius digs itself in silt and rotten plants, and respires with the help of skin. This fish has the certain abilities to forecasting a drought: having a presentiment of rough drought, fishes dig in silt deeper, and fall into catalepsy.
When the rain season comes, adult fishes leave the refuges. They at once start to hunt various insects flying to water, and even try to catch butterflies and dragonflies flying above water. During the rain season from eggs fry hatch. The part of them may appear in temporary reservoirs unsuitable for life, but some ones may get in other rivers and lakes where there are good conditions for life. Fry is very tiny – the length of just hatched fry does not exceed 2 – 3 mm. But they grow quickly, and to the end of the second month of life reach the length of 4-5 cm. At the age of about half-year young fish already can take part in spawning.

Shovel-tailed kuchimba (Kuchimba rutricaudis)
Order: Toothcarps (Cyprinodontiformes)
Family: Notobranchiids (Nothobranchiidae)
Habitat: Zinj Land, seasonal freshwater reservoirs – drying rivers.
Egg-laying toothcarps are characteristic inhabitants of seasonal reservoirs in Africa. Due to the development of a specific habitat, they managed to survive in the era of anthropogenic pressure, although many small-ranged species and intraspecific forms died out at that time. However, they were able to avoid competition with live-bearing toothcarps introduced to the Old World by people, because they live in drying reservoirs, where these aliens simply do not survive. In due course of evolution, they have developed new survival strategies, and one of them is displaying by shovel–tailed kuchimba, a small species of egg-laying toothcarp that lives in seasonal reservoirs of Zinj Land.
This species does not stand out in its appearance among the many related forms common across Zinj Land and mainland Africa. The body length of adult kuchimba individuals does not exceed 5 cm. It is a fish with a strong robust body; head with large eyes is about one-fifth of the total length of the fish. Superior mouth is capable of opening wide: fish feeds on larvae of mosquitos and other insects, often swallowing insects falling on the surface of the water. Fins are rounded; dorsal and anal fins are shifted to the back of the trunk. A notable feature of the appearance is the thick muscular tail stalk. Tail fin is short and rounded, with strong thick rays.
This species is characterized by pronounced sexual dimorphism in coloration. The male is slightly larger than the female, golden in color with a black “mesh” on the sides formed of the edges of the scales; back is dark. Male’s head is almost black, and the shining eyes stand out brightly against this background. Often there are local forms that differ in the shade of the general color and the intensity of the mesh pattern in the male. In the female, the general color of the body is greenish; mesh pattern is present only on the back. The variability of female coloration in local forms is much less expressed. Pectoral and pelvic fins are transparent. Male’s tail fin is bordered by a bright red stripe on the posterior edge – it is the widest and brightest in dominant individuals. In females and subordinate males, tail fin is brown.
The life expectancy of these fishes is determined by the time of existence of their native reservoir, so the fishes are literally in a hurry to live. They eat intensively and grow rapidly: sexual maturity comes at the age of 3 weeks. Male is characterized by aggressive behavior towards other males: he drives them away from his territory, clinging to the caudal fin and hanging on it, or striking their sides and stomach with his snout. In front of the females, the male arranges a colorful display, shaking his whole body in clear water near the surface, and spreading his tail fin like a fan.
Kuchimba spawns by burying eggs in the bottom silt, which is covered with a hard crust in drought, protecting the lower layers of the soil from the heat of the sun. To do this, a pair of fishes digs themselves into the silt vertically, pressing against each other’s sides and vibrating the whole bodies. During the spawning, tail fin serves as a shovel. Hence the name of the species: “kuchimba” means “to dig” in Swahili. The male digs more actively, outthrowing clouds of silt into the water, hiding the fish from possible predators like water beetles. During the breeding season, the male manages to make 2-4 clutches with different females. Sometimes, with the rapid drying of the reservoir, fishes arrange the last spawning act, burrowing themselves with their last strength into the wet mud, and die there, surrounded by their own fertilized eggs. When the reservoir dries up, their bodies do not have time to rot, and they quickly mummify in an upright position. During the rainy season, the decomposition of these corpses enriches the water with organic matter, and promotes the development of small invertebrates that serve as food for their offspring.
Fertility is up to 100 eggs with a dense envelope. Eggs successfully survive the dry season in the silt layer under a crust of dry mud. However, it is more difficult for buried eggs to spread on the legs of animals, as it happened in killifishes of the human era. Therefore, this species settles in the wet season along the rivers, already in adulthood. At the beginning of the rainy season, the eggs hatch, and snake-like fry with reduced fins crawl up, writhing like worms. They begin to feed actively and grow rapidly, turning into young fishes.
Life expectancy does not exceed six months. Occasionally, separate individuals manage to survive up to a year if they get into non-drying reservoirs that persist in riverbeds. However, the “elderly” males clearly do not enjoy the attention of females because of the pale color of the tail. Very old females are able to give offspring; their clutch can number up to 150 eggs, and young males often spawn with them.

Tiny snail cleaner (Helicichthys hygeius)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: Great Antigua, slowly flowing rivers, ponds and bogs.

Sometimes health of certain animal may depend on other species of live beings, and sometimes the connection may look too strange. Vertebrates are hosts of various helminths. Life cycle of these parasitic worms is connected to change of various hosts at different stages of development of worm. Frequently larvae of helminths parasitize in freshwater snails during any time, and then pass from them to the final host.
At Great Antigua many species of animals live, and some their parasites pass the part of life cycle in large freshwater snails of families Ampullariidae, Viviparidae and others. But the evolution had given to snails the unexpected assistant – one local fishes.
Small translucent fish about 25 millimeters long constantly keeps near large snails. The body of this fish has only some dark spots on back, and on side thin longitudinal silver strip stretching from eye up to the basis of tail fin is visible. It is a symbiote of snails, tiny snail cleaner. The body of snail cleaner is prolonged and thin due to what fish can penetrate into pallial cavity of snail, not causing it of anxiety. The pointed head of snail cleaner permits this fish to clear delicate snail gills of parasites accurately. Fish constantly keeps near the snail, not swimming out from it more than to 10-15 centimeters. Only in case of extreme danger snail cleaner can leave a snail “cared” by it, but after that it necessarily searches to itself for the new host mollusc. If danger threatens to the fish, it hides in shell of snail. Sometimes it even squeezes into shell of snail when mollusk retracts into it, and waits danger, having covered in pallial cavity of snail. Enemies of tiny snail cleaner are water beetles, bugs and leeches.
Tiny snail cleaner eats various invertebrates found near snails and on its body. It eats rotifers and smallest larvae of midges and mosquitoes. This fish is able to eat planarias, harming to snails strongly, without harm for itself. Other fishes do not eat planarias because of their poisonous slime. But the biggest benefit of this fish is received not only by snails cleared by it, but also by various species of vertebrates of Great Antigua. Tiny snail cleaner, in addition, eats swimming larvae of helminths searching for snails to pass the next stage of life cycle. Therefore contamination by helminths of vertebrats of Great Antigua in habitats of tiny snail cleaner is much lower, than in similar areas where this fish is not present at the same number of snails.
Tiny snail cleaner belongs to viviparous species. The complex ritual previous to pairing is lack at this species. Male and female are coupled at the meeting of their host snails. The sperm received by female, keeps viability for a long time, therefore female is able to bring posterity within several months after the only pairing. Embryos in ovoducts of female do not lose connection with it up to last moment before birth. Stimulus for their birth is the presence of large snail having no symbiote fish. When such snail comes nearer to closer distance, the female of tiny snail cleaner leaves its own host snail and quickly gives rise to one well developed young fish for other snail. The anal fin of female of tiny snail cleaner has lengthened front edge and resembles the male gonopodium a little. At the birth moment the edge of fin turns off in tube like an ovipositor. With its help the female places newborn fry right in pallial cavity of snail. After the fry birth it quickly swims back to its own host snail. Fertility of the female can make up to fifty young fishes for three months of life. Sometimes within one day the female gives rise up to three young ones in shells of different snails. Right after the last birth in her organism next embryo starts to develop.
Transparent young tiny snail cleaners are completely independent and very active. They clear host snail of parasites, and the first weeks of life hide in its shell. At bi-monthly age young tiny snail cleaner reaches sexual maturity. Life expectancy of this fish seldom exceeds 20 months.

Barbed cave live-bearer (Caecopoecilichthys barbatus)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: caves of Central America (Yucatan).

Picture by Lyagushka

In Neocene viviparous fishes of Poeciliidae family have a true evolutionary blossoming. Among them many freshwater species had evolved, and the significant number of these fishes had developed sea inhabitancy. Among poeciliids in human epoch there were some species of low-specialized troglobionts – cave species made only first steps in development of gloomy world of caves.
From human epoch millions years had passed. In Neocene among live-bearers the true cave species deeply specialized to such habit of life, barbed cave live-bearer, had evolved. It lives in underground waters of Yucatan Peninsula and was widely settled in various caves due to unpretentiousness and endurance.
It is rather large species of fishes at which the sexual dimorphism is clearly expressed: the female is much larger, than male. Length of female is about 15 sm, male is only about 10 cm long. Female and male very strongly differ from each other not only in size, but also in shape, and also in features of behaviour. Female is massive and has deep body. It swoms slower and eats larger prey. Male is faster and has prolonged body. It has smaller mouth and eats small aquatic animals.
The shape of barbed cave live-bearer is the evidence of millions years of evolution in underground habitats. It is completely blind fish at which even rudiments of eyes was not kept. Only two holes on head indicate former presence of eyes at far ancestors of this species. Instead of lost sight this species has well advanced organs of lateral line and set of receptors located on head. Related to barbed cave live-bearer fishes living in rivers and sea have no wattles, but at cave live-bearer around of mouth the outgrowths similar to short wattles are developed. They are especially numerous on bottom jaw, because of what this species has received the specific epithet “barbatus” – “barbed”. The length of these outgrowths reaches 20 – 25 mm; they are plentifully covered with sensory cells.
The body of barbed cave live-bearer is lack of pigmentation and has pinkish-white color. The skin of fish is covered with thin transparent scale. Fins are wide; back and anal fins are shifted back, to tail. At males anal fin is turned to long mobile gonopodium which basis is covered with small scales. The length of gonopodium makes about half of length of male’s body. Tail fin is trapezoid; at its back edge there is small cutting dividing it to lobes. Pectoral fins are fan-shaped and mobile.
This fish species is widely settled in underground waters of Yucatan and adjoining areas of Central America. It is connected with the fact that barbed cave live-bearer can live in water of various salinity – from fresh up to oceanic. Using sea caves, it settles from one underground river into another one.
Barbed cave live-bearer represents strongly expressed predator. At this one wide mouth able to extend to tube and literally to suck prey is developed. This fish eats larvae of insects and other water animals living in caves. If from vaults of cave bat drops and falls in water, bearded cave live-bearer willingly eats them, especially representatives of small species or cubs. It swallows prey entirely – in conditions of caves as in ocean depths it is practically impossible to have strict diet or to eat more or less regularly, therefore the present species of fishes uses poor food resources of cave to the full. Jaw bones are connected by mobile ligaments, and gullet and stomach can stretch strongly.
Similarly to all relatives, this fish is viviparous. However, breeding rate at barbed cave live-bearer is much slower, than at fishes living in open reservoirs. The female of this species gives rise only to one young fish at once. But fry is very big – its length reaches one third of length of female, and it has all chances to survive. Nevertheless, females of barbed cave live-bearer frequently attack young fishes of its species. Within one year the female bears posterity no more than four times, but it is enough of it to provide reproduction of species in conditions of rather isolated reservoir with poor food resources. Right after birth male and female do not differ from each other in size, but further male finishes growth earlier and matures faster. However, in connection to cannibalism of females, the number of males in population is insignificant – it mounts about a quarter of the whole population. Young fishes mature at the age of 1 year, and life expectancy makes not less than 8 years.

Dwarf stomatobius, “mouth fish” (Stomatobius pusillus)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Live-bearers (Gambusiidae)
Habitat: Zinj Land, rivers.
During evolution live organisms develop freakish forms of mutual relation – from symbiosis up to parasitism and superparasitism in various displays. One of freakish ways of coexistence with other species was developed by tiny viviparous fish living in Zinj Land – dwarf stomatobius, the descendant of guppy (Poecilia reticulata) which had been widely settled in tropics of the Earth by people for struggle against malarial mosquitoes. This fish species differs from the ancestor in very dim colouring and special way of life. This species has entered relations of commensalisms with disproporcichla (Disproporcichla micrandra), large fish living in the same places. Stomatobius lives in one of the most reliable shelters in the river – in the mouth of large females of these fishes when those ones brood their fry. Less often stomatobius fishes settle in mouths of other representatives of cichlid family. Life in mouth of the representative of so protected species bears the great benefits: it is reliable protection against the majority of predators of small and medium size, and also carries constant supply by food.
The shape of stomatobius is adapted in top degree to imitation of disproporcichla fry. It is tiny fish (length of adult individual does not exceed 15 mm) with the translucent short body, short fins and rather large eyes. As fish grows, its colouring becomes similar to colouring of the host fish fry. Sight sense has the important role in imitation of host fry – during the growth fish imitates changes of host fry colouring. Life of stomatobius is very short – no more than one month from birth to death. It grows and changes synchronously with fry, imitating one of them, and is fed on the same food, as they are – on infusorians, tiniest worms and larvae of crustaceans. This species behaves tolerantly in relation to fry of host fish, and only competes to them for food, but not in the greater degree, than young fishes compete to each other.
Life cycle of stomatobius is closely connected to presence of mouthbrooding fishes near to it. If such fishes are not present, the development of fry of this species is considerably delayed – it develops physiologically, but growth is considerably slowed down. It happens, that in such condition females of stomatobius reach sexual maturity and they are fertilized by “homeless” males. But, though the fertilization occurs normally, ovocytes in ovaries of the female do not develop while she will start to grow.
If the female succeeds to find a couple of cichlids preparing for brooding, it stays near to them, waiting for a right moment and driving potential competitors away. If there is no host fish of suitable species beside, stomatobius fishes behave to each other rather peacefully, but the presence of the necessary fish changes the behaviour of stomatobius. Females differ in greater aggression, but let males fertilize themselves. Spawning of potential hosts and the excretion into the water of the chemical substances, accompanying this event, render stimulating influence on the female. She starts making cautious, but active attempts to get in mouth of brooding fish. As a rule, she makes it at night, cautiously penetrating under the operculum of the host fish. If not disproporcichla is chosen as the host, stomatobius correctly defines by smell what individual is brooding eggs. When the host fish opens operculums, stomatobius squeezes under them and gets into the mouth. This fish almost on the spot starts to benefit the host fish, gathering parasites attached to gill arches.
If the fertilized female has penetrated into the mouth of host fish, she almost at once starts to spawn posterity. Eggs and embryoes develop in her ovaries as on the conveyor, and with a current of water through gills stomatobius fry leaves a mouth of the host.
When host fry leaves the parent, stomatobius is also compelled to leave a refuge and to lead independent life. At this time, if the female was not fertilized before its settlement in mouth of the host fish, at them the courtship season begins: males, having changed camouflage colouring to courtship dress, gather in thickets of plants. Courtship colouring of the male is monotonous bluish-silvery with dark matte back. Females come to their smell, then fertilization follows, and within the next two weeks the female spawns up to fifty youngs one by one. Two types of development of stomatobius females are, probably, the beginning of division into two separate species, at one of which fertilization takes place before the life in mouth of the host fish, and after it at another one.

The idea about existence of this fish was proposed by Simon, the forum member.

Antiguan live-bearing crucian (Baripoecilia cyprinoides)
Order: Toothcarps (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: Great Antigua, rivers and lakes.
In Neocene, Central America and the surrounding areas of North and South America became the site of a kind of evolutionary experiment. Live-bearing fishes, numerous here back in the human era, in due course of evolution have evolved into a large-sized class and have become ecological analogues of a variety of predatory and herbivorous fishes – pikes, needlefishes, barracudas, flying fish and cyprinids. Giants appeared among them, but some species remained small. At the Great Antigua island, in conditions of predation by cichlids and large live-bearers, as well as in the presence of sufficiently extensive habitats, a large omnivorous species of live-bearers – Antiguan live-bearing crucian – appeared.
The size of an adult of this species is about 20 cm. The physique of the fish slightly resembles some representatives of cyprinid fishes living at the continents: it is a powerful fish with a deep muscular body. In its outlines, Antiguan live-bearing crucian slightly resembles crucian carp (Carassius carassius) of the human epoch. This fish has a small head, large eyes and a mouth that can extend into a small tube. The lips are covered with a lot of villi, which allows it to hold small prey and scrape microscopic algae from a solid substrate. Pectoral fins are rounded – this fish is not able to swim fast, but it has good maneuverability in thickets of plants and among snags. Pelvic fins are greatly reduced and represent several thickened rays connected by a thick membrane. In males, they are larger than in females, and on the inside of these fins they develop spines that serve to hold the female during mating. The anal fin of the male turned into gonopodium – a mobile copulatory organ. Male also differs from female in a more elongated body shape and a slightly smaller size. Tail fin of this species is trapezoidal, not divided into lobes.
Coloration of fishes of both sexes is the same, with striated pattern. General color is gray with a metallic sheen; back and vertical stripes on the sides are black. Fins are transparent, and only in the male the gonopodium is colored black. These fishes keep in schools of 20-30 individuals. The food of this species includes soft aquatic plants, lower algae and sedentary animals, as well as insect larvae.
Antiguan live-bearing crucian is remarkable in its original breeding strategy. Females of this species give birth to only a few (3-5) large independent fry at once. Offspring are born every 2 months. Newborn fish reaches a length of 25-30 mm. This is due to the fact, that in the oviduct of the female fry receive additional nutrition: they develop villi on their belly skin, with which they attach to the wall of the oviduct. Their attachment causes the growth of blood vessels in the wall of the oviduct, and the mother’s body supplies nutrients to the developing offspring. The young fishes group into one-size schools to defend themselves from enemies. A large fry is an obstacle to cannibalism, and newborn fry themselves already can hunt juveniles of other species. Also, fry differ from adults by greater mobility: they move into the lower reaches of rivers and can live for some time in mangroves, settling along the coast. Sometimes the current carries these fishes into the open sea, and they can settle on neighboring islands.
At the age of 1 year, young fishes reach sexual maturity. Life expectancy is up to 15-20 years.

Minute bivalvophila (Bivalvophila minuta)
Order: Toothcarps (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: rivers of Africa, Congo basin.
The human epoch has left an indelible mark on the history of the Earth’s biosphere. The large-scale introduction of alien species to various areas of the Earth led to the appearance of their descendants in the Neocene in places where they were unable to settle naturally. In some cases, they have seriously affected the appearance of ecosystems, especially of the island ones. In more stable continental ecosystems, the role of descendants of introduced species is much smaller, but among them there are forms that show some bizarre specialization.
Bivalves that live in the Congo River in the upper layer of the river soil have a whole set of symbionts – among them there are small crustaceans, rotifers, nematodes and other worms. Along with invertebrates, a very small fish species is found in the shells of mollusks – minute bivalvophila, a descendant of the mosquitofish (Gambusia affinis), introduced to Africa in the human era to control the number of Anopheles mosquito.
Bivalvophila is a dwarf fish species: the body length does not exceed 30 millimeters, but usually it is even smaller – up to 20 mm. Body of an adult fish is depigmented, translucent with a slight yellowish tinge. Also, adult fishes of this species have degenerated eyes and are almost blind – they can only differ light from darkness and distinguish the movement of large objects. Fins are short, rounded and transparent. Body of this fish is covered with slippery protein slime and lacks scales.
Minute bivalvophila lives exclusively in the mantle cavity of living bivalve mollusks and feeds on organic substances that the mollusk sucks into the shell with a current of water. Fish simply crawls inside the shell on the body of the mollusk and gathers food, which is filtered by its gills. This worsens the nutrition of the mollusk and slows down its growth. However, in the presence of fish in the mantle cavity of the mollusk, there is a positive moment: the fish cleanses the mollusk from ectoparasites, making it healthier.
The method of reproduction of fish is unusual. It retained the characteristic live-bearing of its ancestors, but this species became a hermaphrodite. Therefore, any two individuals from the same mollusk shell can mutually fertilize each other. Gonopodium is reduced, copulation occurs with the help of an everting cloaca. The rate of reproduction of this species is relatively slow due to its small size and special life strategy. Fry of bivalvophila are large; 1-3 individuals are born up to 10-13 times a year. They are mobile and immediately leave the shells of the host mollusks through the exhalant siphon. At the fry stage, this species settles: fry swim actively, have good eyesight and pigmented skin; their color is piebald – brown spots of various sizes on a transparent background.
Having found by the smell a shell that is not inhabited by relatives, or in which only one relative lives, the fry penetrates into the shell of the mollusk through an inhalant siphon, and undergoes metamorphosis in the mantle cavity, acquiring features of an adult. In addition, a young individual can live without a host for some time, although this leads to developmental abnormalities. Such individuals are stunted, not reaching even half the length of a normal individual. They often settle in empty shells, but this is not a complete replacement for a live mollusk. Usually such individuals remain infertile.
The life expectancy of this species can reach 5 years.

Glassy boreopoecilia (Boreopoecilia speculum)
Order: Toothcarps (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: North America, freshwater rivers, coastal zone of lakes in the temperate climate.

Picture by Lyagushka

Western mosquitofish (Gambusia affinis) was one of the most successful species of the human era. To control the Anopheles mosquito, this species was widely settled throughout the tropical regions of the Earth, and thanks to its high adaptability, the fish managed to accustom in new habitats. Therefore, its descendants are found in many areas of the Earth of the Neocene epoch. At home, in North America, its descendants managed to significantly expand their range after the ice age, and even master life in a temperate climate. In the fresh waters of North America, glassy boreopoecilia lives – an ecological analogue of sunbleak and other cyprinid fish. This fish, which lives near the surface of the water, has an elongated body; the unpaired fins are shifted far back. Sexual dimorphism is expressed in this species: the body length is up to 20 cm in the female and 15 cm in the male; the male is slimmer than the female. This fish has large eyes, and its superior mouth with elongated jaws can open wide and slightly protrude forward.
Coloration of this fish is easily recognizable. A narrow black stripe stretches along the entire back from the tip of the snout, turning into a black sling on the tail stalk at the base of tail fin. Along the sides of fish, from the tip of the snout across the eye to the sling on the tail, a wide silver stripe stretches, masking the eyes and preventing the predator to recognize the outlines of the fish by its shine. The shine of this strip is especially intense in young ones. The belly is bluish-gray.
Glassy boreopoecilia is a relatively cold-resistant species: it is able to winter under the ice for 1-2 months.
The favorite habitats of this fish include the areas of rivers overgrown with aquatic vegetation with floating leaves, or covered with thickets of floating plants. Fishes prefer to stay in ambush under floating objects.
This species is exclusively zoophagous; the food consists of aquatic insects, mosquito larvae, fish fry and tadpoles. Also, glassy boreopoecilia is able to jump up to a height of up to 1 meter, snatching insects in flight. Sometimes it attacks small birds flying over the water, clings to them and drowns them. While the corpse of such prey has not drowned, fishes in a school tear it to pieces and eat it.
Mating usually takes place in the spring, with males actively chasing females and competing for the right to mate with them, pushing each other away from the female. The birth of offspring occurs about 3-4 weeks later. Fertility is up to 100 juveniles up to 15 mm long at birth. The birth of offspring continues from the end of spring to the beginning of summer, for about 2 months. After that, there is a second wave of mating, after which the juveniles are born at the end of summer. Fry keep in thickets of floating plants and among coastal thickets, feeding on small insect larvae and planktonic crustaceans. For the first time after birth, they are transparent; then they get a shiny stripe on the side.
Sexual maturity comes at the age of 2 years; life expectancy reaches 13-15 years.

Hibernating cryopoecilia (Cryopoecilia hibernator)
Order: Toothcarps (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: North America, rivers and lakes in temperate climate, Miche-Nama Lake.

Picture by Lyagushka

Mosquitofish (Gambusia affinis) has significantly expanded its range in the human era, and thanks to human-made introduction it is found in almost all areas of the Earth suitable for its life. In Neocene, its descendants make up a significant part of the tropical ichthyofauna. At home, in North America, the descendants of mosquitofish have significantly expanded their range, and are found even in temperate climates. In the process of evolution, they have developed cold resistance, and can even winter under ice. The most cold-resistant species among the descendants of mosquitofish is hibernating cryopoecilia. It is found in places where rivers are covered with ice for up to 4 months a year.
Compared with its ancestors, this fish has significantly increased in size – the length of old individuals reaches 25 cm. It has short rounded fins and a muscular body, rounded in cross-section. Female is larger and heavier than male. Male has a long mobile gonopodium with a fleshy base. The coloration is nondescript – light brown with a darker back and translucent fins; there is no sexual dimorphism in the coloration. Head is short, with a wide terminal mouth, allowing feeding in all layers of water. Eyes are small, orange or yellow.
This fish prefers to live in rivers and drainage lakes, keeps at the bottom in thickets of underwater plants and hunts a variety of invertebrates. With the onset of cold weather, fish buries itself into the ground to a depth of 1 meter, working with its head and fins, and at the bottom of the dug hole, it curls into a ring, covering its head with a tail fin, and is covered with abundant viscous protein-based slime. This slime protects the body coverings of this fish from freezing. An additional adaptation for survival during wintering is skin respiration.
Hibernating cryopoecilia is a zoophagous species capable of eating even planarian worms inedible for other fishes. The usual diet includes mosquito and midge larvae, leeches and oligochaetes, small snails, fish fry and amphibian larvae.
Living in harsh conditions led to the formation of a characteristic life strategy. Hibernating cryopoecilia has a small fecundity, but the juveniles are very large and independent. Mating takes place in early summer, and the female bears fry until spring, including during the wintering, when the development of offspring slows down greatly. Early in the spring, the fish comes out of hibernation and after the melting of snow and ice, the females give birth to offspring. Juveniles look like adults and can immediately feed on relatively large prey. The length of the fry at birth is up to 40 mm, and it can immediately eat prey half the size of its own length. There are only 9-12 juveniles in the brood; the survival rate of the offspring is very high.
Young fish take part in reproduction from the age of 4, and their life expectancy reaches 30 years.

Southern False Molly (Pseudopoecilia splendens)
Order: Toohthcarps (Cyprinodontformes)
Family: Livebearers (Poeciliidae)
Habitat: Murray River and other fresh waterways of South Eastern Meganesia.

Picture by Lyagushka

The introduction of the Gambusaia as a means to control mosquitoes has been perpetrated in many places of tropical zone of the Earth, and thus it has many descendants in the Neocene.
One such form is the Southern False Molly, a form of livebearer that has, from its tiny drab ancestor, come to be ornate and colourful, resembling a Molly or Killifish in shape and colour. It reaches a body length of about 7 centimetres, males have a prominent tail and dorsal fins, which are large, rounded, brightly coloured with patterns of yellow, orange and black. The body colour is a reddish orange, with indistinct dark cross stripes.
These fish form mid-sized schools of 15-20, and tend to cluster in stands of underwater vegetation. They feed mostly off algae, water plants and small invertebrates.
Females give live birth, fertilisation is internal, and the males endeavour to court the female by flashing his fins in a fluttering fashion, though they will also try to mate quickly by force. Gestation occurs internally and lasts 35-45 days; females produce up to 120 fry. Lifespan in the wild is about 7 years.
Theses livebearers and their relatives can tolerate brackish and even saltwater conditions, which has led to the evolution of its relative, the Estuarine False Molly (Pseudopoecilia maculata). This species inhabits the mangrove forests and estuaries that flow into Eyre Gulf. It differs by smaller size and less flashy colouring, the body is silvery, and fins are pale yellow with dark spots. Breeding habits are generally similar, but in the first few days fry are guarded during ebb times to guard them from being washed away.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Atlantic live-bearing notatrout (Enantiosalmo viviparus)
Order: Toothcarps (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: Atlantic Ocean, coastal waters, rivers in temperate and subtropical climates.
In the Neocene, viviparous fish of Poeciliidae family made an important evolutionary step – they settled to the seawater and began to explore a variety of ecological niches that the marine habitat can offer. Some of them spend a full life cycle in seawater, while others have retained their connection with fresh waters and spend part of their life cycle in rivers or in brackish coastal waters. Among the latter one, there is Atlantic live-bearing untrout, one of the northernmost marine species of live-bearing fishes. It is an anadromous fish, that feeds in seawater, but still reproduces in fresh waters. This is a relic of one of the early stages of adaptation of toothcarp fishes to life in the sea.
An adult individual of Atlantic live-bearing notatrout grows up to 40 cm in length. It has a wide cylindrical body with a powerful tail stalk and deep forked tail fin. Dorsal and anal fins are shifted to the posterior half of the body. Head has large eyes and wide terminal mouth. Body coloration has two variants – marine and riverine. In its marine dress, fish is silver-blue with a dark greenish-blue back. Under the influence of decreased salinity and odors of river water, the coloration of fish changes: it turns dark green with a brown back and separate silvery “sequins” on the body.
Atlantic live-bearing notatrout fattens in the sea off the coast of North America, at a depth of up to 20 meters. This species eats mainly planktonic crustaceans: shrimps, euphausiids and copepods. Jellyfishes, worms and fry of marine fish serve as an addition to the diet.
For reproduction, these fishes return to the rivers. Males remain in estuaries or in the lower reaches of rivers. Females go up the rivers very far – up to the upper reaches of the rivers, where they give birth to offspring in the streams. Getting to the upper reaches of the rivers, they swim in large schools and are able to jump up the low waterfalls, making jumps up to 2 meters high. Having reached the upper reaches of the rivers, fishes rest for a while, after which they spread out along the streams and occupy territories in shallow waters. They clearly prefer areas overgrown with small-leaved plants or water moss, and drive their relatives away from occupied areas. At night, such females quickly spawn a large number of fry, after which they hide in shelters. Fecundity is up to 300-400 small juveniles. They immediately hide among the shoots of water plants, gradually settling down the river. In the first weeks of life, a significant number of fry die from small predators like aquatic insects and crustaceans.
After giving birth, the females move sluggishly, hardly resist the flow of water and rest for several days without eating. At this time, they are very vulnerable, so some of the fishes die from predators. After getting stronger, the females begin to feed, and at night they gather in schools and are sinking into the sea. This method of reproduction becomes a great stress for the female’s body, and after the delivery, she recovers for a long time. Nevertheless, the female of Atlantic live-bearing notatrout repeats the breeding cycle up to 6-8 times in her life. Female usually dies after spawning the last brood of fry, being unable to recover from stress.
Males mate with females who have arrived from rivers and join their schools. After mating, the development of eggs begins in the female’s body, but during the winter it slows down significantly and resumes only in the spring.
Young female is fattened in the sea for three years of life, reproduces the first 2-3 times annually, then every second year. Males begin breeding already in the second year of life. The lifespan of females does not exceed 15 years; males live about 10 years.

Unpaired heteroxiphos (Heteroxiphos dispar)
Order: Toothcarps (Cyprinodontiformes)
Family: Live-bearers (Poeciliidae)
Habitat: rivers of tropical areas of South America.
In the Neocene, the vast river network of the Amazon and Hippolythe represents a place of rapid evolution of freshwater fishes developing various survival strategies in the process of evolution. Even after the global ecological crisis at the boundary of Holocene and Neocene, this colossal river system was a relatively species-rich natural community.
Live-bearers represent a characteristic component of the ichthyofauna of this area. Their life strategy turned out to be relatively successful – a relatively large parental contribution to the offspring pays off with a high survival rate of juveniles. In the process of evolution, forms displaying various modifications of this method of reproduction appeared among them.
A widespread species of South American live-bearers is unpaired heteroxiphos, a descendant of the swordtail (Xiphophorus) of the human epoch. This species has developed a specific breeding strategy aimed at increasing the parental contribution to the rearing of less numerous brood.
A characteristic feature of this species is strictly expressed sexual dimorphism. The male is small, about 10 cm long; the female, on the contrary, is very large, up to 25-35 cm long. The body shape is characteristic of live-bearers: smooth flat back, small superior mouth, dorsal fin strongly shifted back. Belly is rounded, especially in the female. Both fishes have the same soft coloration – greenish-yellow with spots on the back and upper part of the sides. Fins are rounded; tail fin is slightly divided into upper and lower lobe; the male grows a sword-like outgrowth on the lower part of the caudal fin. Anal fin of the male is transformed into a gonopodium.
These fishes live in forest rivers, preferring clear or “black” water. They have large eyes and good eyesight; a significant part of their diet consists of insects that have fallen into the water, as well as water beetles and bugs, dragonfly nymphs and shrimps. Also, these fish eat the fry of other fishes.
Heteroxiphos lives in a paired family, which persists for a very long time – during a number of breeding cycles. This is due to the distribution of responsibilities in the family. Each pair occupies a certain territory of shallow river waters with thickets of plants and other shelters. Female of this species is large and aggressive: she guards the territory, male and offspring, and is able to expel fish of comparable size from its home area. Female has a robust skull and hard snout, with which she acts like a battering ram. Male is a more peaceful creature: he fertilizes his female and takes care of the brood. Female fertility is up to 40-50 fry 3-4 times a year. Male “pastures” them in the thickets, masticates small animals for them, guards the vicinity of a flock of young animals and, in case of danger, drives them into shelter, simultaneously giving a sound alarm signal to the female. If this male dies, a new “bachelor” male usually begins to court the female. However, in the first weeks of courtship, he behaves aggressively towards the young of this female. He detects by smell the pregnancy and time of delivery of the female, and eats the offspring of the female from the previous male. Having felt the readiness of the female for fertilization, he fertilizes the female and begins to take care of his own offspring. Sometimes one male can live on the borders of the territories of two females and fertilize them both, and then takes care of a large school of fry of different ages. Due to the small size, the mortality of males is greater than that of females, and often females remain unfertilized. These extra females, who have not found a mate, are gradually reborn into males. They stop growing, the ovaries are reborn into testes, and outwardly such “Amazons” look like very large males, up to 20 cm long, with a somewhat deformed, but workable gonopodium. The offspring from the mating of such fishes with ordinary females consists only of females. In females, the greatest mortality occurs during growth.
Sexual maturity in males comes at the age of 7-8 months, in females – at 15-16 months.
Life expectancy reaches 10-13 years.

Round-mouthed kibotichthys (Kibotichthys cyclostomus)
Order: Toothcarps (Cyprinodontiformes)
Family: Madagascar suckers (Kibotichthyidae)
Habitat: Madagascar, the upper reaches of the rivers of the eastern part of the island.
In the human era, the native ichthyofauna of Madagascar was threatened with extinction due to the mass introduction of alien species into the fresh waters of the island. The freshwater ecosystem of the island turned out to be so fragile that its own freshwater fish species quickly died out without leaving any descendants, and in Neocene, the island’s ichthyofauna consists exclusively of descendants of introduced species and natural migrants to freshwater after the end of the human era. In due course of evolution, all the available ecological niches of the fresh waters of the island were distributed among them. One of these fishes, a descendant of the swordtail (Xiphophorus helleri), became an ecological analogue of labeos and loricariid catfish, switching to feeding on microscopic algae growing on solid substrates.
This fish called round-mouthed kibotichtis inhabits the non-drying rivers of the eastern part of the island. The body of kibotichthys is robust, cylindrical in shape, with deep and strong tail stalk; tail fin is trapezoidal in shape with a long string growing from its lower edge. In females, this string is short, reaching a quarter or a third of the length of the body; in the strongest males, the length of this string is approximately equal to the length of the body. Body of this fish is covered with small scales. The length of an adult male is up to 12 cm (not including its tail thread); the female is about 15 cm long.
The anatomy of this fish has changed significantly compared to the ancestral form. Its head has become wide and flat; eyes are slightly shifted upwards. Mouth is shifted to the lower part of the head and has turned into a sucker adapted for scraping microscopic algae and sedentary animals from a solid substrate. Lips are covered with corneous villi. Pectoral fins are broad and fan-shaped, with hard anterior rays. Pelvic fins are reduced and turned into attachment organs. From each of them, only one thick fin ray with small spikes persisted, which helps to hold on to the asperities of the substrate. Dorsal fin is rounded and transparent with a black border. Fishes have evolved a characteristic signal indicating claims to the territory: trembling of the opened dorsal fin for 5-6 seconds. It lacks swim bladder. Body color is brown; sides below the lateral line are yellowish-beige; belly is white. Tail string, on the contrary, has a contrasting cross-striped black and white coloration: when fish is attacked by a predator, it distracts its attention and allows the fish to escape. The broken tail string regenerates, but its pattern becomes paler. This fish is very secretive and cautious, hiding in shelters at the slightest danger. The name comes from the word “kibota”, meaning swordtail in one of the Malagasy languages.
Like its ancestor, this fish species is viviparous. Male’s anal fin is modified into a movable gonopodium, the tip of which reaches the posterior edge of the caudal fin (excluding the tail string). The courtship ritual involves the male chasing the female and holding her by the tail stalk with the pelvic fins. At this point, fertilization occurs, and the partners swim away from each other. Pregnancy lasts about 2 months. Fertility is up to 5 large, well-developed juveniles (length at birth – up to 15 mm). During the year, the female gives birth to offspring 3-4 times. Young individuals are able to keep in the current with the help of mouth sucker immediately after birth. Their pelvic fins are hook-shaped, but they quickly develop additional spines. Young individuals prefer to stay in the thickets of water moss.
Sexual maturity comes at the age of 8-9 months; life expectancy is up to 8-9 years.

River needle-jawed live-bearer (Potamobelone acutirostris)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Predatory live-bearers (Rapaciliidae)
Habitat: rivers of Great Antigua.
At the boundary of Holocene and Neocene the most productive communities of ocean, coral reeves and plankton, had suffered irreparable damage as a result of catastrophic processes happened in biosphere. With their disappearance in crisis period the biological variety of oceans had sharply decreased. When conditions acceptable to life had started to restore, survived species had started to evolve actively. Caribbean Sea and Antilles became the center of active speciation of live-bearing fishes. Their ability to live in fresh and sea water, and also high survival rate of posterity were the features determined their evolutionary success.
In shallow waters of Caribbean Sea, in rivers and estuaries live-bearing fishes make an appreciable part of the variety of ichthyofauna. In rivers of Antilles species of fishes of other families were kept, but live-bearers make a considerable part of ichthyofauna there. Some river live-bearers have related species in Caribbean sea. The needle-jawed live-bearer living in lower reaches of rivers of Great Antigua is the close relative of sea lancemouth. This fish lives in deep parts of river channel and occasionally leaves in brackish water of rivers mouth.
The body length of river needle-jawed live-bearer reaches half meter at weight about 400 gramms. Colouring of sides of this fish is silvery with slanting cross strips; back is dark green. Eyes at fishes of both genders are red. River needle-jawed live-bearer keeps in shadow of plants floating on the water surface, or under tree trunks floating in the river. When fish leaves shelter, its colouring becomes uniform silvery.
The most remarkable feature in appearance of this species is the structure of jaws: they are extended and pointed at tips; the bottom jaw is longer than top one and has triangular section. On its bottom side sharp keel stretches. The bottom jaw serves as the hunting weapon: fish pins catch up with the help of this adaptation. Protecting itself against predator, river needle-jawed live-bearer puts to aggressor deep stab and slash wounds by jaws. This tactics of defense makes it very dangerous species: this fish is very excitable and sometimes attacks ground animals swimming in water, taking it for aggressor. By this feature river needle-jawed live-bearer is similar to swordfish of Holocene epoch, which had also attacked objects had not represented any danger for it.
Similarly to many predators, river needle-jawed live-bearer is solitary species. But it is not aggressive relatively to congeners and does not avoid their neighbourhood. At places rich in food this species forms small congestions changeable by structure without any hierarchy. The social behaviour at this species is not advanced; therefore this fish does not form true schools and does not pay attention to adult congeners only because they are too large to be a food.
River needle-jawed live-bearer eats mainly fish. It catches prey up with fast rush and tries to put to it wound by bottom jaw. The swallowed catch has characteristic traces of attack: stab and slash wounds. Small catch may be literally cut half-and-half by impact of the bottom jaw. River needle-jawed live-bearer can eat its own fry.
The male of this species is smaller than female and its “sword” is shorter. It eats smaller catch and keeps in shallow waters of rivers and in shallows of river mouth. Male eats not only pelagic catch; it frequently digs by bottom jaw invertebrates at the bottom of shallow rivers. Females live in deeper places of rivers, therefore for pairing male leaves habitats and moves to river channel. To involve the female male makes high vertical jumps above the water surface.
Courting for the female, male becomes brightly colored: stomach gets nacreous shine, anal fin and gonopodium turn black, and the tip of “sword” becomes red. Male swims near the female, pushing its back and sides. If the female is ready to pairing, it stops and inclines to the side, turning cloaca to the male.
Spermatozoids of male keep viability for very long time, and fertilized ovocites may run the diapause. As a rule, one pairing with the male is enough to the female to give birth up to three hatches of fry. Once in three weeks the female gives rise up to five large youngs (up to 5 cm long) with short jaws. First few weeks of life at young fish long bottom jaw characteristic for species grows, and then on its bottom side “keel” starts to grow. Young fishes of this species are also active predators. They eat at first larvae of small insects, then fishes and water beetles. Because adult fishes are cannibals, young ones hide from adult fishes of their own species. For this purpose young fishes simply turn vertical pose among roots of floating plants. Adult fish prefers to not attack animals seeming to it too “high” – it estimates the angular size of object in vertical dimension. Therefore it does not attack such young fish even seeing it. Due to such simple tactics the part of fry may escape of attacks of adult fishes.
Young fishes become able to breeding at the age of 11 – 13 months, and life expectancy of this species reaches 20 years (females live for longer time, rather than males).

Dwarf lancemouth (Nanobelone esociformis)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Predatory live-bearers (Rapaciliidae)
Habitat: Great Antigua, streams and shallow rivers in forest.
Climatic changes and anthropogenous pressure had resulted in extinction of many species of large fishes in fauna of rivers of Caribbean Sea basin. Their place was occupied by unpretentious and quickly breeding small species among which viviparous fishes of live-bearers family (Poeciliidae) dominated. In Neocene they realized the received advantage, having formed some independent families of viviparous fishes differing by anatomy and habit of life. Various representatives of these families inhabit fresh waters of Central America, Caribbean Sea, Panama Passage and even Pacific coast of America. In various habitats speciation of these fishes actively passes, and among them rather strictly specialized species evolve.
In shallow forest streams of Great Antigua island small live-bearing fish lives – dwarf lancemouth. Despite of size (the length of body of the male is about 5 cm; females grow up to 8 cm), it is active top-skimmer predator, the relative of terrible sea species of lancemouth. But dwarf lancemouth may represent the threat only for larvae of mosquitoes and various small insects fallen in water.
The body of this tiny fish indicates prompt and ruthless predator. It is arrow-like and strongly extended. Unpaired fins are shifted back; abdominal fins are reduced up to several thick fin rays. On internal side of abdominal fins of the male short sharp spikes develop. Head of this small fish is flat and narrow, with goggled mobile eyes; bottom jaw is only a little longer, than top one.
Colouring of body of this fish is longitudinal-striped, silvery with black strokes. Male and female out of breeding season differ not only in size, but also in colouring of eyes. At males iris of the eye is bright blue, at females eyes are black.
This fish lives in forest rivers and streams, keeping in shallow water under leaves of marsh plants hanging above water. It eats insects (the basic forage is mosquito larvae), and can eat fry of other fishes.
For courtship display male chooses sites where through forest canopy sunlight shines. At the male ready to pairing appreciable dark blue shade appears on back. Male shows to the female back shining dark blue color and eyes sparkling in sunlight. It is not afraid of attack from above: sunlight shines on surface of water, and it hides presence of the male. It is capable to fertilize several females in succession, and the period of courtship proceeds at him till about one week. At fertilization of females the male actively uses abdominal fins with spikes. With their help the male “saddles” the female, jumping to her back and squeezing her body right behind operculums. Preparation for pairing ritual resembles rodeo a little: the male tries to keep as long, as it is possible, on the female which tries to shake from itself the importunate male. If the male kept on a back of the female long enough, she stops “gallop”, and freezes at the surface of water, having slightly bent on one side: it is a signal to pairing. At this moment male “jumps off” from her, fertilizes the female fast, and again is engaged in courtship display, showing itself in beam of sunlight.
The male is territorial; it drives off other males from the site. If it is necessary, it furiously battles to them: male bites contenders to fins, and tries to seize by jaws for tips of their jaws. If the male succeeds to do it, the opponent appears disarmed: it can not open mouth. Using it, the unpunished site owner drags him for some time, and then lets off at the border of territory.
Fertility of dwarf lancemouth is very small – usually at the female only 1 – 2 young fishes are born simultaneously. Birth of fry repeats each 2 weeks. Small fertility does not represent threat to survival of species: it is compensated by high degree of survival rate of young growth: the newborn fry reaches third of length of parental individual, and congeners or posterity of other fishes will not eat it any more. The newborn fry at once can eat fry of other fishes and larvae of insects. It grows quickly, and already at four-monthly age the female of dwarf lancemouth gives rise to posterity the first time. Life expectancy of this species in wild does not exceed two years.

Segregated callopoeciliops (Callopoeciliops dispar)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Deep-bodied live-bearers (Altipoeciliidae)
Habitat: fresh waters of Central America.
In early Neocene when coral reeves degraded and the richest fauna of sea shallos had disappeared, in Caribbean Sea the active adaptive radiation of live-bearing fishes began. They had appreciable advantages in comparison with sea species – these fishes were less specialized rather than their sea neighbours and were able to live both in fresh and in sea water. Being mainly small and tiny animals they had kept a sufficient variety after the global ecological crisis, and at early Neocene had sufficient potential for new evolutionary break. In conditions of rather low competition in restored ecosystems of early Neocene the tendencies shown at the level of species and genera differences were realized to the full, having formed great number of species differing by ecology and habit of life, and belonging to several families.
Differences of various species include other features except for anatomy, for example behavioural features. Different courtship rituals of the male reliably interfere with crossing of closely related species that also have resulted in formation of some species of live-bearing fishes of Neocene. The additional factor of isolation was various shapes of copulating organ, the gonopodium, in some cases preventing pairing of different species and occurrence of hybrids.
Males and females of live-bearing fishes often differ in colouring and size strongly. It is especially precisely shown at fishes from fresh waters of Central America belonging to genus Callopoeciliops (“the beautiful fish similar to Poecilia”). Their males and females would be hardly for classificating as representatives of the same species basing at the appearance, therefore this species had received the specific name “segregated”.
The body of callopoeciliopses is high, of rounded outlines, compressed from sides, especially at males: it is a common attribute of all representatives of Altipoeciliidae (“deep-bodied poecilias”) family. Callopoeciliopses are externally similar to a crucian, and lead a similar habit of life, eating vegetative forage and small animals in shallow rivers of Central America.
Back fin of these fishes is high and pointed; its forward rays are thick. On fin some small “pearl” spots shining in sun light are scattered, permitting to representatives of species to find out each other. At females the basis of back fin has black spot.
For these fishes the sharp sexual dimorphism in colouring and size is very characteristic. The female of this species is large (up to 20 cm long), grayish with several black spots stretching like a chain along sides. Its back is greyish green – it helps to disappear from predatory birds attacking from above. The male of segregated callopoeciliops is smaller, rather than female: its length is about 10 cm. In quiet condition male is spotty, bluish with black spots on back and head. In rivers of Central America there are many fishes much brighter in colouring, but not many of them may surpass the callopoeciliops male in multicoloring in courtship season. During the courtship ritual at the male of this fish bright courtship dress hiding in usual life is shown. The male of segregated callopoeciliops differs in very variative colouring – color of different individuals varies from entirely cherry red up to cobalt blue and emerald-green with numerous transitions between such vatieties. Frequently there are bicoloured fishes at which head or fins have another color, rather than body, and also fishes of transitive colouring. Occasionally among males black individuals with color shine and also fishes with black spots on colored background appear. The integrity of colouring is broken a little with eyes – at fishes of both genders and any colouring they are silvery and shining.
When the male is not occupied with courtship display, its bright colouring is shown poorly – the shade on scales is swept up only, and black individuals are simply darker a little than usual males. Courting at the female, male is colored especially brightly and tries to show itself to the female as favourable, as possible. It tries to keep in bright sunlight to make colouring as better visible, as it is possible. In courtship season the whole loop of males of different colors, up to ten fishes, stretches behind the female ready to pairing. They compete among themselves: push each other away from the female, having at the moment of clush darked shade. Sometimes the strongest male seizes tails and fins of contenders, biting and breaking them off.
Female does not interfere with battles of males and behaves phlegmatically enough and indifferently in their environment. It couples to several males in succession; therefore ritual fights of males do not guarantee at all, that strongest of them will have the posterity.
Because all deep-bodied live-bearers are rather deep-bodied fishes, it is more difficult to them to pair, rather than to live-bearing fishes of usual shape. But at them one original adaptation facilitating this important process is developed. The pectoral fin of the male has thick strong top ray with small bristles. At pairing with the female male clings by this fin its pectoral fin, and till the pairing hangs for some seconds on the female. Sometimes at once two males cling to one female – one fish on each side of its body. But only one of them can enter soft roe into its genital ducts. In courtship season pectoral fins of females appear torn because of active male courts, but they restore quickly.
Out of pairing season fishes of different genders keep separately. Schools of females swim in main river channel, and small males hide in underwater thickets at shallow water and lead secretive habit of life. Males come to females when their schools come nearer to the coast. Rains are stimulus to pairing: noise of rain and the rise of oxygen contents in water result fishes in excitation. After rains continuing till some days in succession, males start to color brightly, and females gather in shallow waters.
Fry develop in organism of the female rather quickly: usually female spawns fry each two weeks till the half-year. Young fishes are tiny (no longer than 8 – 11 mm), but their number is large: up to 200 ones in one pack. The soft roe of males keeps viability in oviducts of the female for a long time, but without additional pairings the amount of fry decreases in each new pack. But fry of last packs are even twice larger, rather than in first one.
Fry of callopoeciliops gather to schools kept up to adult condition, and hide among rich underwater vegetation. During the mass breeding of these fishes in river gulfs shoals of thousands of young fishes swim. Males of this species grow slowly in comparison with females. Young fishes reach sexual maturity in different time: males at one-year-old age already take part in courtship games, and female is ready to fertilisation only at the age of one and half, or even in two years.
Gradually shoals of young fishes divide by size and gender. Males form separate school and remain to live in thickets of underwater plants, and females schools swim to deep areas of rivers farther from coast. They willingly keep under “rafts” of floating plants, feeding there on larvae of insects and eating young roots.

Spiny hypotenuse fish (Hypotenusichthys aculeatus)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Vertical, or Head-standing live-bearers (Verticalichthyidae)
Habitat: mountain rivers of Central America and the south of North America (Mexico).

Picture by Fanboyphilosopher

In Neocene live-bearers have reached the great evolutionary success in tropics of New World. Various species of these fishes live in rivers and in sea, turned to vegetarians and predators, giants and dwarfs. They have developed various ecological niches and have fancifully changed in order to use resources of their habitat in the best way. Among them the unusual family of head-standing live-bearers had appeared; the representatives of this group in normal position keep body vertically, head downwards.
The transitive form from fishes of habitual shape to verticalichthyids is kept in mountain rivers of Central America. It is unusually looking fish which is named spiny hypotenuse fish for original appearance. It is the representative of live-bearers living in current and eating tiny animals and algal pellicles growing on firm substratum.
The body of spiny hypotenuse fish has triangular outlines from sideview. The backbone of this fish in normal position is positioned at the angle of about forty degrees to substratum. The outline of stomach is almost horizontal, and approximately from the beginning of anal fin the contour of body is sharply bent upwards at the right angle to line of stomach. Head of this fish is wide and flattened. The part of stomach, directly adjoining to substratum, is slightly concave and forms a sucker which helps to attach to surface of substratum. Body of fish at the level of abdominal cavity is almost triangular in cross section. When hypotenuse fish stands a head against current, water stream presses it to substratum. The top part of back is narrow and compressed from sides, and tail stalk is deep. The length of adult fish does not exceed 20 cm.
The back fin of spiny hypotenuse fish in the degree of development represents a transitive stage between normally advanced fin of typical fishes and strongly reduced fin of head-standing live-bearers. Fin rays in it are thicken and short, and the membrane is reduced – it covers only the bottom half of each ray (hence the name – fin rays are prickly). Tail fin is short and deep, blaed-like, with elastic poorly branching fin rays. Its bottom part adjoins to the anal fin stretching along the entire “cathetus” of fish from below upwards. At males first (actually they are bottom, located at the substratum) fin rays are transformed into copulating body – gonopodium. Belly fins are very reduced and hook-like, numbering only 4 – 5 thick rays which have almost merged together. They are additional bodies of attachment, and also serve for keeping of the partner during the copulation. The bases of belly fins are fleshy and mobile. Pectoral fins are wide and fan-shaped.
Spiny hypotenuse fish swims very badly. If current breaks it from substratum, it at once falls on bottom and tries to attach to stones or to driftwood. In thickness of water it swims very slowly and clumsily.
The scraping mouth of this species is half moon-shaped. Lips are thick and fleecy; they serve for scraping of algae and sedentary animals from substratum. Small eyes are located near corners of mouth. At the feeding fish moves forward by short jerks, moving by tail and anal fins.
The body of spiny hypotenuse fish is colored silvery-grey with blue shade. Back is dark blue; on sides small black irregular-shaped spots are scattered. In courtship season anal fin of male turns bright red with transparent edge and dark spots at the basis. Courting the female, males attach near to her, pushing each other away, and try to hook by belly fins against belly fin of the female. Sometimes at once two males succeed to do it, and they begin original “struggle” by gonopodiums, pushing the contender away from cloaca of the female. Copulating male stays with the female for a long time, not allowing to another males to copulate with her.
Pregnancy lasts for about two weeks. In ovoducts of the female embryos start the development not simultaneously, and after the only pairing the female gives rise to one young fish in each three days within half-year. Newborn fish of this species about 2 cm long has the shape typical for fishes. It has only underdeveloped sucker on stomach. At week age it begins to attach to plants and stones, gathering food from them. At bi-monthly age the young fish represents a tiny copy of adult individuals. At the age of 16 – 17 months the young hypotenuse fish becomes sexually mature.
Close species of hypotenuse fishes inhabit rivers of Central and North America:
Motley hypotenuse fish, or driftwood fish (Hypotenusichthys maculatus) lives in slowly flowing forest rivers running into gulf of Mexico. It has short and deeper body of rhomboid outlines about 12 cm long. Colouring of this fish resembles the surface of driftwood pierced by larvae and overgrown with moss: the basic background is brown with several randomly scattered black spots and light brown strokes; wide black stroke always stretches across the eye. Tail and back fins are transparent. The belly sucker represents two longitudinal plicas of skin. This fish keeps more often among driftwood or the flooded tree trunks, and scrapes tiny animals and algae layer from the surface of driftwood.
Overturned hypotenuse fish (Hypotenusichthys reversus) inhabits flatland rivers and lakes of Central America, overgrown with floating plants. It is the smallest species of the genus – the length of adult individual does not exceed 5 - 6 cm. It leads way of life unusual to this group of fishes: this species uses sucker for attaching to the bottom side of leaves of floating plants where it eats small animals. Body of this fish is short and deep, “humped”, almost square in shape; the backbone of fish stretches diagonally in this “square”. On the belly side of body there is well advanced sucker looking like longitudinal plica of skin. The belly fins are transformed into attachment devices and help fish to attach to thickets of small-leaved floating plants. They represent long hooks with tiny denses on the internal side. Their length makes approximately one third of general length (“diagonal”) of fish. Head is short and deep, but mouth is of scraping type, like at other species of genus. Colouring of body of this fish is silvery with marble green pattern, helping to hide among plants. On tail fin there is a large oculate spot – false “eye” of yellow color with black center. This fish is able to swim better, rather than other species of the genus, but only at short distance. After fast jerk it tries to hide in thickets of plants.

Mangrove verticalichthys (Verticalichthys striatus)
Order: Cyprinodontiformes (Cyprinodontiformes)
Family: Head-standing live-bearers (Verticalichthyidae)
Habitat: mangrove thrickets at the coast of Caribbean Sea, coast of Great Antigua.
In Neocene viviparous fishes of tropical areas of America had reached the particular variety. In human epoch they were presented by rather small species, but some Neocene live-bearers became true giants. Among them both sea and freshwater species had evolved. Some species of Neocene live-bearers had got morphology strange and unusual to fishes. These ones are species presenting vertical, or head-standing live-bearers family – their manner of movement has determined their name. In rest head-standing live-bearers keep body almost vertically, or having small inclination. Being scared, they seek safety in flight in usual for fishes horizontal position.
Mangrove verticalichthys is the largest species of family. Its length reaches 40 – 45 cm, and height of body is only 5 cm. The body of fish is strongly extended, and head with small mouth makes approximately the fifth part of the total length of fish.
Fins of verticalichthys are advanced in such a manner that normally helps it to move in vertical position. At this fish anal fin stretching along the bottom side of body is strongly advanced; because of it cloaca of fish is shifted forward on breast. Actually at swimming fish anal fin is directed back. It waves, and fish slowly swims forward. The forward part of male’s anal fin is transformed to gonopodium with mobile muscled basis. Wide and mobile pectoral fins help fish to keep balance. Also with their help verticalichthys can move upwards and downwards, gathering forage from the bottom. Tail fin is short and wide; when fish swims in vertical position, it is compressed, and body of fish seems pointed from above. At occurrence of danger fish turns to horizontal position and swims to shelter with the help of tail fin. Back fin of fish is reduced and represents low leathery crest with rudiments of fin rays.
At females abdominal fins are small and rounded, and at males they are transformed to hook-like captures, permitting to keep the female. Fin rays are strong and supplied from the inside with set of small denticles.
Colouring of mangrove verticalichthys is chocolate-brown with several thin longitudinal strips of white color on sides. One of strips stretches from tip of snout across an eye (additionally masking it) up to the basis of tail fin. Pectoral fins are transparent.
Verticalichthys fishes keep solitarily or in small groups in mangrove thickets. They are able to move dexterously in vertical position among roots of mangrove trees. Striped colouring helps them to mask good in such environment. These fishes can live in water of various degrees of salinity – from almost completely fresh water in river mouths up to ocean water of normal salinity. During outflow these fishes can remain at shoaliness. In this case they dig in ground with the help of movements of anal fin, and lay, having put outside only a head.
Food of verticalichthys is made of various small aquatic animals – worms, crustaceans, molluscs and tiny fishes. In fresh water they eat larvae of water insects. Head of this fish is extended and has small mouth. Mouth can be extended as a small tube, helping to dig small animals out of ground.
Verticalichthys fishes breed during all year. Fishes pair in vertical position, turned by stomach to stomach of each other. At this time male keeps female by abdominal fins. In two months after pairing female gives birth posterity - 5 – 6 rather large translucent young fishes; till one year it bears posterity 3 – 4 times. Newborn verticalichthys fishes have body shape characteristic for these fishes, but swim in horizontal position more often, than adult fishes. Also at young fishes back fin is more advanced, but decreases later. Young ones of verticalichthys keep in thickets of water plants, preferring the freshened areas of mangrove thickets and river mouths. Gradually on body of young fishes dark longitudinal strips appear. In older age they extend and turn brown color, and intervals between them lose transparency. At the age of about 4 months young fish gets colouring characteristic for adult individuals, and at the tenth month of life young fish can take part in breeding.
Close species live in coastal waters of Caribbean Sea:
Acrobat live-bearer (Algopoecilia acrobata) living among seaweed thickets differs in massive constitution and rather short body. It is one of primitive kinds of the family, keeping a lot of features of usual fishes.
Golden needlefish (Chrysospinichthys melanostriatus) is a small fish living in rivers at southern coast of North America. This species very seldom goes to brackish water of river mouths and absolutely never swims to sea. The body length of adult individual is about 20 cm, and body height seldom exceeds 15 mm. Golden needlefish has very long head – it makes one third of total length of fish and has small mouth at the tip. The body of this fish is colored golden-yellow and has expressed metal shine. Along each side from tip of snout up to edge of tail fin the deep black strip lasts. All fins are transparent, except for black strip on tail fin.
Abdominal fins both at males and at females are reduced and turned to attachment organs. Abdominal fin at this fish represents two strongly thicken fin rays covered with bristles from the inside. With the help of these fins males keep females at pairing, and fishes of both genders cling to plants to keep in watercourse.
The female of golden needlefish gives rise up to 4 – 5 large fry at once, but within one year it bears up to six broods. Fry of this species is transparent, large and short-headed, only a few similar to adult individuals.
Pelagic verticalichthys (Euverticalichthys meropelagicus) is a small fish: total body length is about 25 cm. Colouring of body is silver-gray with thin and slightly twisting longitudinal strips of dark grey color on sides. This species lives far from coast, in thickets of sea spinach – characteristic floating plant of Caribbean Sea. Pelagic verticalichthys constantly keeps in thickets of this plant, and, as against to the majority of species, keeps the most part of time turned a head up. This fish eats small crustaceans, gathering them from leaves and roots of sea spinach. Also this fish eats fry of other species of Caribbean live-bearers. The mouth of pelagic verticalichthys can extend to tube, soaking up prey in a split second.
Abdominal fins at fishes of both genders are transformed to hooks with which help fishes keep each other at pairing, and also cling to roots of sea spinach during the storm. This fish swims with the help of fluctuations of ribbon-like anal fin which has fleshy basis and length of about one third of total length of fish. Fertility of these fishes makes only one young fish once per ten – twelve days. But the length of such fry is about half of mother’s length, and survival rate of such large posterity is much higher, than at the set of tiny fry. Newborn pelagic verticalichthys at once can eat fry and other kinds of food characteristic for adult fishes.

Great false swordfish (Xenoxiphias magnificus)
Order: Needlefishes (Beloniformes)
Family: False swordfishes (Xenoxiphiidae)
Habitat: tropical and temperate waters of all oceans; in summer in warm currents comes to the border of polar waters.
In early Neocene, after “plankton accident”, when productivity of ocean started to increase, various groups of fishes began to evolve in direction of pelagization. Among them there were needlefishes – the group of long-jawed sea and brackish-water fishes. In Neocene their descendants became specialized pelagic fishes making special family of false swordfishes. It includes various species – from schooling pelagic ones up to semi-deepwater fishes. And the most remarkable representative of this family lives in warm waters of all oceans is great false swordfish, very large fish similar to swordfish (Xiphias) of Holocene epoch. It is one of the largest osseous fishes up to 6 meters long (including rostrum), weighting up to 300 kgs.
Great false swordfish is perfectly adapted to inhabiting in open ocean. It has short strong body of “scomber-like” shape – rather deep, with short strong tail stalk. Unpaired fins of this fish are shifted in back half of body. They are narrow and peaked. Pectoral fins of false swordfish are crescent and have very rigid forward rays. At movement they act as elevators and serve for balance.
The most remarkable feature, which has determined the name of fish, is its rostrum. Upper jaw of this fish is longer, than bottom one; it is peaked and very firm. The length of rostrum makes about one third of general length of fish. Bottom jaw hardly reaches half of length of top one. It is wider and slightly covers rostrum from sides. On the bottom jaw there is a firm skinny keel stretching back to breast.
The skin is firm, covered with small scale, and also is similar to emery paper to the touch. Such rough skin smooths over turbulence of water, reducing thus resistance at movement. Colouring of body of great false swordfish is blue with silvery stomach. On root of tail there is black triangular spot turned by top to the head.
Great false swordfish is fast fish of top layers of water. It can accelerate movement up to 100 kms per hour, chasing prey. Having gathered speed, fish can jump out of water, making jumps up to 10 meters long. This species eats smaller fish and squids, but there are cases when this fish attacks sea birds flying above surface of water, and punches them by rostrum. Great false swordfish does not have any tooth in mouth, and swallows prey entirely.
In clutch of this fish it totals up to 100 million eggs. Many sea fishes are pelagophils – they spawn eggs in water and do not care of posterity. Great false swordfish represents the exception of this rule. It spawns eggs on objects floating on surface of waters – this behavioural feature had remained from needlefishes, its ancestors. For spawning male finds tree trunk floating in water and protects it from congeners, waiting for appearing of female. It involves females to its territory by high vertical jumps, loudly splashing in water. The female ready to spawning quickly reacts to such appeal. The pair of fishes spawns eggs on roots or branches of tree trunk, and clutch stays on them as a long tape of slime quickly swelling in water. Inside it there are tiny eggs which develop during 2 – 3 days. Fry of great false swordfish is lack of characteristic rostrum. Young fishes live in plankton till 5 months, gradually taking the body shape characteristic for adult individual. The one-year-old fish has length of about 20 cm, and rostrum makes about the fifth part of it. By ten years the fish reaches length of 4 meters, and six-meter specimens are old, twenty years old individuals.

Short-beaked sarganella (Sarganella brevirostris)
Order: Needlefishes (Beloniformes)
Family: False swordfishes (Xenoxiphiidae)
Habitat: Atlantic ocean, temperate, subtropical and tropical latitudes of both hemispheres.

Picture by Fanboyphilosopher

False swordfishes are characteristic pelagic sea fishes of Neocene epoch. They are descendants of needlefishes and form various, but unite by origin group. The common features of these fishes are short or moderately lengthened body (in contrast to very long body of needlefishes), high crescentic tail fin, narrow and rigid pectoral fins. All species of false swordfishes are zoophagous fishes. Large species (for example, great false swordfish (Xenoxiphias magnificus)) are solitary predators and eat large prey, and smaller species are schooling planktophags eating crustaceans, small fish and cephalopods.
Small species of these fishes are ecological analogues of mackerel and other pelagic fishes of Holocene. In contrast to giants of family, these species have short pointed snout. Typical representatives of schooling false swordfishes are sarganellas. They are medium-sized fishes – the length of representatives of various species changes from 20 up to 70 cm. They have moderately long body, flattened top part of body, and projecting leathery keel stretching from throat prior to the beginning of anal fin. Scales are very small and deeply buried in skin. Rostrum of sarganellas is very short – its length does not exceed the length of head.
Fins of sarganellas have the shape characteristic for quickly swimming fishes. Pectoral fins at them are narrow and long (their length is approximately equal to length of head in common with rostrum), and abdominal ones are strongly reduced. Back and anal fins are peaked and shifted to back half of body. Tail fin is high and narrow; it has the characteristic crescent form and is very resilient. Sarganellas can accelerate momentum over 60 kms per hour, and at the short distance they make throws at speed over 80 kms per hour.
Far from coast in Atlantic schools of one of sarganellas species live; it reaches the length of about 50 cm. The body of these fishes has silvery-blue color with metal shine, and tips of top and bottom lobes of tail are colored black. It is short-beaked sarganella, the most “snub-nosed” species of the genus. Its toothless jaws are very short and form only approximate similarity of “sword”, characteristic for false swordfishes, more resembling thickened bird’s beak.
Short-beaked sarganella eats small pelagic animals – crustaceans, herring squids and fry of various fishes. This fish swims very quickly and catches up the most high-speed pelagic animals. Attacking small schooling prey, fish puts to it wounds by jaws, not slowing down its own movement. Hunting of sarganellas for such animals resembles beating more – fishes surround a shoal of prey and swim around it, as if incidentally striking impacts to prey. Jaws of these fishes can compress strongly and crack armours and skulls of prey. Fishes swimming right after first ones pick up animals wounded or killed by fishes swimming ahead. But, when the school of sarganellas surrounds prey and forms a ring, first fishes get the prey killed by individuals swimming ahead. Because of such hunting tactics sarganellas can eat small prey effectively only in school. The school of these fishes is lack of the leader, and any fish can be both among attacking ones, and among “marauders”. Attacking larger fishes and squids, which do not form dense congestions, sarganellas operate independently from each other, and swallow only their own prey.
These fishes inherited from needlefishes the way of spawning. Though sarganella belongs to pelagic fishes, it spawns eggs on plants – usually on floating algae. Frequently these fishes migrate for spawning to algal fields, developing plentifully near to New Azora island. As in the most cases the meeting of suitable substratum for spawning is accidental, these fishes developed one more adaptation for spawning. Eggs at sarganellas develop in small portions (up to 4 – 5 thousand ones simultaneously, that is too smal amount for pelagic fish), but they keep viability for a long time, keeping in ovaries of the female. The meeting of floating plants is the most powerful spawning stimulus. Having searched the suitable substratum, sexually mature fishes begin spontaneous spawning which passes very roughly. Males within several minutes turn brightly colored (their colouring becomes more sated, and on the body some indistinct vertical strips appear), and females gather to unisex school. Males start to display their force, making high jumps from water and sparkling in sunlight by shining sides. When their excitation reaches apogee, they rush to school of females, and start to pursue females one by one or in pairs. Swimming above plants, females spawn portions of eggs, which on the spot become fertilized by males. During 15 – 20 minutes spawning is finished, and fishes abandon eggs, not caring about posterity.
Posterity of sarganellas represents tiniest pelagic larvae. They are predators and grow very quickly. Larvae of sarganella eat fry of other species of fishes, shrimps and larvae of cephalopods. By the end of the second year of life fishes reach approximately 80 % of length of an adult individual and start to breed. Life expectancy of short-beaked sarganella seldom exceeds 7 years, and small species start to lay eggs at one-year-old age and live no more than 4 years.
Sarganellas are typical species of fishes of open ocean, but among them there are species meeting near to coast. In Neocene epoch some kinds of these fishes live in World ocean. Pacific, or golden sarganella (Sarganella chrysopectoralis) replaces the Atlantic species in tropics and subtropics of Pacific – from Panama passage up to Indonesia. Occasionally these fishes swim to Caribbean Sea and equatorial area of Atlantic. It differs in appreciable golden shade of scale and in larger size – about 60 cm. Males of this species in courtship colouring shine pure gold, even with reddish shade. Black tail fin contrasts with this background. Pacific sarganella is an active predator; its prey includes pelagic octopuses and squids, and also large fish. These sarganellas do not form numerous schools, and their congestions number no more than two tens individuals.
Hawaiian sarganella (Sarganella hawaiiensis) lives in northern part of Pacific Ocean, from the latitude of Hawaiian Islands and along the Asian coast up to Big Kurils, and comes into sea of Okhotsk in summer. It is a small species of the genus – the largest individuals are up to 30 cm long. But the small size is compensated by high number: schools of this sarganella total up to 300 – 500 thousand individuals. Colouring of fishes is silvery with three thin longitudinal strips on every side and dark back; one dark strip passes from tip of snout across the eye to root of tail. These fishes eat small planktonic crustaceans and fish fry. Hawaiian sarganella spawns in the summer at the northern border of an area – in coastal areas of Pacific Ocean, in thickets of brown algae.
Pointed sarganella (Sarganella acuta) lives in tropical Indo-Pacific region. It is usual at coast of Meganesia and islands of Indonesia, and also in tropical area of Indian Ocean. These fishes do not leave from coast, and their small schools frequently come to reeves to hunt local fishes. The present fish is the largest species of the genus – the average length of adult individual is up to 70 cm. Body is more prolonged, than at other species; this species is similar by constitution and habits to barracudas (Sphyraena) of Holocene epoch. Body colouring is blue with black cross strips. This fish does not avoid fresh water and frequently catches prey in river mouths and mangrove thickets.
Southern sarganella (Sarganella australis) is the hardiest species of this genus. It lives in southern part of the Atlantic, Indian and Pacific oceans, in the area of temperate climate. In summer schools of these fishes come far to the south, to coast of Antarctica. It is the smallest species of sarganellas – large individuals seldom exceed 25 cm in length. The body of present species of fishes is silvery, and tail fin has black strip on back edge. The rostrum is a little shorter than length of other part of head. Southern sarganella breeds in thickets of brown algae at the coast of South America and Falkland Islands.

Striped brevisarga (Brevisarga fasciata)
Order: Needlefishes (Beloniformes)
Family: False swordfishes (Xenoxiphiidae)
Habitat: Pacific Ocean, subtropical and warm temperate zones of the Northern and Southern hemispheres.
In Neocene, needlefishes represent one of the main pelagic fish groups of the ocean. Their diverse representatives display remarkable examples of convergence with herring, mackerel, horse mackerel and even swordfish. A similar lifestyle has led to the appearance in needlefishes of features of external similarity with unrelated groups of pelagic fishes. One of the unusual species of pelagic needlefishes is Pacific striped brevisarga. In fact, it is a very short-bodied needlefish with deep body: the body length of an adult is about 20 cm (not including the jaws) with a body height of up to 15 cm. Body shape of brevisarga is unusual for needlefishes – the forehead of this fish rises sharply upwards; the outlines of the body are close to rectangular, and behind the bases of dorsal and anal fins, the body sharply narrows into a strong four-sided tail stalk. Body of brevisarga is strongly laterally compressed, and the unusual profile of the head is formed due to the development of a ridge of tough skin stretching from the rostrum through the forehead to the beginning of the dorsal fin.
Body of brevisarga is adapted for fast swimming. Tail stalk is rigid, with two longitudinal dermal keels extending along its sides. Tail fin is sickle-shaped, deep and rigid. Dorsal and anal fins are almost the same shape, pointed and slightly bent back. Pectoral fins are crescent-shaped; their bases are raised above the midline of the body; pelvic fins are short and narrow, pressed against the sides and abdomen when moving.
The coloration of brevisarga is characteristic of pelagic fish – the general color is bluish with thin vertical stripes of dark blue forming a characteristic pattern in the form of ripples on the back and in the upper part of the sides. Belly and lower part of the sides are silvery with pronounced metallic sheen; fins are gray. Eyes of this fish are large, yellowish in color.
Brevisarga belongs to zoophagous species. Mouth of this fish is equipped with small numerous teeth. Unlike ancestral needlefish species, brevisarga has a short snout with jaws unequal in length: the lower jaw protrudes from under the upper one by 6-8 cm. Brevisarga feeds on soft-bodied planktonic organisms, filtering them through an open mouth when moving. In connection with this method of feeding, its mouth can open wide. The elongated lower jaw is covered with grainy skin, which dampens swirls of water when moving: this is an example of convergence with swordfish, in which the sword-like outgrowth of the upper jaw performed a similar function.
It is a schooling fish gathering in shoals numbering up to several tens of thousands of individuals. Brevisarga does not come close to the shores, preferring the open ocean.
The adaptation to the pelagic lifestyle has gone very far in brevisarga: these fishes spawn in the water without needing a substrate. Small eggs are glued into a long strip by gelatinous slime. In the clutch, there are up to a million small eggs, which swell strongly in the water. Slime drifts apart by the time the fry hatch (the incubation period is up to 3 days). At the age of one year , the young fish reaches a length of 4-5 cm . At the age of 4, brevisarga reaches sexual maturity; life expectancy is up to 20 years.

Striped herring mullet (Clupeomugil pentastriatus)
Order: Mullets (Mugiliformes)
Family: Pelagic mullets (Pelagomugilidae)
Habitat: Tanganyika passage, top layers of water.
Mass extinction at the boundary of Holocene and Neocene has had the most fatally effect at the structure of ichthyofauna. During natural accidents which had determined change of epoch in most degree, there was a catastrophic decreasing of amount of plankton organisms. It was followed with extinction of animals depended on plankton as food source, or passed through plankton stage in life cycle. In particular, pelagic species of fishes - scombroid fishes, tunas, herrings had completely died out. When number of plankton had increased, former eaters had irrevocably died out, but from among benthic and coastal fishes less injured from natural accidents, new pelagic species had started to form. They had mastered rich resources of ocean, having evolved plenty of new species.
Striped herring mullet is the descendant of any coastal mullet fishes. It is medium-sized fish about 20 cm long. Its body is rather narrow and extended: this fish can swim quickly. Large head with widely opening mouth accounts about 1/5 of body length. Fins of herring mullet are moderately long; there are two back fins: soft back fin is well advanced, from prickly back fin five sharp separate spikes serving for protection against enemies remained. Tail fin is forked and wide. The body of fish is covered with small scales, silvery-colored with five blue longitudinal strips. Such colouring is characteristic for some schooling fishes: it prevents predator to distinguish contours of separate fish on the background of other ones. Middle strip is very long: it stretches from tip of snout through an eye (masking it) to tail fin.
Herring mullets live in high sea, not approaching closely to coast. They keep from surface up to depth of 30 meters in huge schools numbering up to 20 - 30 thousand fishes. Fishes eat exclusively plankton crustaceans and fry of other species of fishes.
Spawning occurs two times per one year: the basic one in spring, additional one (the amount of spawned eggs is approximately half less than in spring) in summer. Fertility of basic spawning is over 60 thousand grains of roe. For breeding herring mullets swim to the central part of Tanganyika passage where a plenty of plankton breeds. Such abundance appears possible due to rivers washing off in waters of passage huge amount of organic substances from coast. Near to coast water is slightly muddy from suspension taken out by rivers, but far from coast plankton organisms plentifully breed, providing to herring mullets food at any stage of development. Herring mullets spawn in schools, practically simultaneously spawning in water cloud of eggs and soft roe. In school right before spawning pairs form: each male chooses to itself the female and keeps near to it. Sometimes male snaps the female’s pectoral fin, and she is compelled to “tow” him. But such behavior of fishes proceeds not for long time, and spawning soon begins.
Small eggs develop about one day at the surface of water, very small larvae at once start to eat: in the beginning microscopic phytoplankton, then larger and mobile zooplankton. Fry of this species form one-age schools, kept for a long time, sometimes for all life. Herring mullet grows very quickly: at bi-monthly age length of fry is about 5 cm, one-year-old fishes up to 15 cm long already can breed. Life expectancy is little: no more than 5 years, and 80 % of fishes do not reach even the 3-rd year of life.

Arrownose (Xiphomugil acutirostris)
Order: Mullets (Mugiliformes)
Family: Pelagic mullets (Pelagomugilidae)
Habitat: waters of Central America, tropical Atlantic, Caribbean Sea.

Picture by FanboyPhilosopher

Alongside with needlefishes mullets are the successful group of fishes which have occupied open ocean and waters far from the coast after “planktonic accident”. Among them fast swimming analogues of tunas and other pelagic fishes had evolved. And some of pelagic mullets became dangerous predators, the terror of small pelagic fishes.
One of the largest bony fishes of Neocene is arrownose, the inhabitant of tropical waters of Atlantic and Pacific oceans near the coast of New World. It is the huge pelagic fish reaching almost four-meter length, the far descendant of mullets.
In body outlines this fish is very similar to shark. Only homocercal tail and strongly lengthened snout give to this species some external difference from sharks at first look.
Body of arrownose has streamlined shape adapted to fast swimming. Forward back fin is high and has rigid rays. The second back fin is separated to some rigid triangular finlets suppressing turbulence of water during the movement of fish. Pectoral fins are narrow, lengthened, peaked, and have fleshy bases. During the swimming they nestle against sides of body, and the role of stabilizers is incured with the belly fins shifted forward, which are longer and wider than pectoral ones. Tail stalk is deep; tail fin is also deep, forked and rigid. It is an attribute of the good swimmer – arrownose is able to accelerate momentum up to 50-60 kms per hour and to swim in this mode during several hours, and also to make short throws at speed up to 80 kms per hour. The body of arrownose is covered with large rough scales. Colouring of body of fish is silver-grey; back has the expressed greenish shade. Fins are translucent with dark grey edges.
For arrownose the shape of its head is characteristic. The upper jaw of fish is long, pointed, with cutting lateral edges and slightly protruding keel on the top side. The bottom side of snout is only slightly convex. The snout is covered with rigid rough skin, which helps to suppress water turbulence. Besides the snout is used by fish during the hunting. Large eyes are located in forward part of head, at the snout base. Cutting edge of snout stretches above eyes as rigid “eyebrows”.
Arrownose is a predatory fish eating smaller aquatic animals. Usually its prey includes schooling pelagic fishes and cephalopods. Attacking fish “cuts” them by impacts of head, rushing in their school. Impact of edge of snout in high gear is enough to put deep cut wound or to cut smaller fish half-and-half. Arrownose swims around of school of fishes or molluscs, not giving them an opportunity to escale in flight, and from time to time rushes through the school, striking impacts by snout. After attack fish quietly swims at the place of fight and eats wounded ones and pieces of bodies of prey.
Jaws of arrownose are toothless; firm lips partly replace teeth functionally. On lower jaw symphysis there is the peaked triangular outgrowth which is enters the dredging on the upper jaw; it helps to keep pieces of food.
Arrownose keeps above continental shelf and frequently swims close to coast. It is a solitary fish which relates neutrally to relatives of the similar size – near large school of prey some arrowheads of approximately equal size can feed at once. Young arrowheads frequently become prey of adult individuals.
The spawning season of arrowhead lasts for all year. Males ready to spawning declare themselves, jumping from water vertically and falling back with loud splash. For this purpose they choose floating subjects – tree trunks and the bushes carried out to sea from the continent. In this feature the atavistic element of behaviour of fish is shown: ancestors of arrownose from the mullet stock had similar feature of behaviour – propensity to jumps above floating subjects.
Courtship ritual includes male’s pursuit of the female and biting of her back fin. Sometimes the female not ready to spawning escapes from male’s jaws, leaving to him a sizeable piece of back fin. The female ready to spawning swims for some hours in succession (usually the whole night) side by side with male, and at this time fishes eat of nothing. At the culmination moment, in early morning, female spawns up to 50 million tiny eggs. Male fertilizes eggs, and adult fishes do not care of posterity any more.
Larvae hatch after 36-40 hours. They are completely helpless and eat the tiniest protozoans. The significant part of them perishes within several weeks after hatching. Growing up, fry becomes an active planktonic predator. At one-year-old age arrownose reaches the length of 25-30 cm and gradually passes from plankton to nekton. The greatest growing rate at this fish takes place in the first 10 years of life; during this period fish reaches the length over two meters. At the same time it becomes sexually mature. Life expectancy of this species makes about 40 years.

Unpaired stickleback (Heterogasterosteus polygynus)
Order: Sticklebacks (Gasterosteiformes)
Family: Sticklebacks (Gasterosteidae)
Habitat: rivers and brackish bays of Central and Western Europe.

Picture by Lyagushka

Sticklebacks were among the most successful fishes of the Holocene epoch. Rapid growth, the ability to live in fresh and seawater and parental care – these features helped this group of fishes to maintain a fairly high number in the epoch of biological crisis at the boundary of Holocene and Neocene. In early Neocene, the descendants of the survived species began to actively explore the temperate and cold waters of the northern hemisphere. Some of them retained universality in physiology and behavior, while others, on the contrary, have got features of specialization.
The lower reaches of rivers and brackish sea bays of the Atlantic coast of Europe are the habitats of one of the peculiar representatives of Neocene sticklebacks, a relatively large unpaired stickleback. It is a descendant of three-spined stickleback (Gasterosteus aculeatus), common fish of the human era, and has preserved the recognizable features of its ancestor. These are three massive conical spikes on the back in front of the dorsal fin and the sides covered with armor of large bony shields arranged in a row. The body of this species is deeper and more compressed laterally compared to the ancestor. Head is relatively large, with a wide-opening superior mouth. Pelvic fins are reduced – only two short spines without rays and membranes remain from them. A low skin keel stretches along the midline of the belly. Tail stalk is equipped with lateral keels and is tetrahedral in cross section. Tail fin is triangular with a shallow notch in the middle of its posterior edge. This fish species is adapted to fast swimming, and is able to hunt live prey in the water column and at the bottom. Body coloration is greenish with small brown spots evenly scattered over the body; belly is yellow.
It is an exclusively zoophagous species: aquatic insect nymphs, fish eggs and fry, as well as carrion and the remains of prey of large predators become food of unpaired stickleback. Cannibalism is also common, partly regulating the number of its populations. Out of spawning season, these fishes stay away from the coast and hunt in the water column and at depth.
A notable feature of this species is an expressed sexual dimorphism associated with the features of reproduction of this species – hence the name of this species. Male of unpaired stickleback is large: it reaches a length of 16-20 cm. It has a dominant role in reproduction, builds a nest, and protects the offspring. Females are small and numerous; the length of an adult female is usually no more than 8-9 cm. Females prefer larger males for reproduction, which favored selection towards expressed sexual dimorphism. The number of males is lower due to mortality from predators eating larger males and parasitic diseases affecting almost 100% of the population.
Spawning begins in spring, when snow melts in the Alps, and the chemical composition of river water changes. At this time, males approach the shore and divide it into many individual territories. Each male gathers stems and plant fibers, and builds a spherical nest with a through passage from them. He binds the walls of the nest with own viscous slime, and from time to time renews them, bringing in new building material. This is a harem species of stickleback: male spawns with several females at once. To attract females, the male gets a particularly bright color – a “neon” blue stripe appears on the sides, shaded from below with a reddish-orange color of the throat and the abdomen, and from above with a black back. Females get dull silver-gray color. The fertility of each female is up to 50-60 eggs. However, among the females, sometimes there are some young males who mimic the coloring of the females, penetrate into the nest of the dominant male and fertilize part of the clutches, leaving them in the care of the nest owner.
The male expels the females immediately after spawning, and takes care of the offspring almost continuously. He ferociously guards the clutch from predators, attacking even armored crabs and crayfishes with his snout blows. He ventilates the nest, and at first takes care of the young. Often the male catches small aquatic invertebrates, masticates them, and “spits out” into the school of fry, providing them with food. At the age of two weeks, young fishes pass to independent life.
Sexual maturity in females comes the following year, in males – two years later. The male lives up to 6-7 years, the female – only 2-3 years.

Japanese river horsefish (Potamohippidium acuticaudis)
Order: Pipefishes (Syngnathiformes)
Family: Pipefishes and sea horses (Syngnathidae)
Habitat: rivers of Japan Islands, thickets of underwater plants.

Picture by Fanboyphilosopher

Changes in biosphere happened at the boundary of Holocene and Neocene had affected the direction of evolution of various live creatures. Some of sea animals had disappeared (extinction had especially strongly affected pelagic species or species spending in plankton even a part of life cycle), others had kept in isolated sites of earlier extensive area. Some animals had compelled to replace habitats to survive. At Japan Islands in Neocene the river species of sea horses had appeared. This fish species had settled in rivers of Japan from Inner Japan Sea during the ice age at the boundary of Holocene and Neocene (actually it had repeated the way of needlefish from Caspium Sea and Black Sea settled in rivers of Europe in Holocene epoch). When the sea level had decreased, between islands isthmuses had appeared; they had transformed Inner Japan Sea to gulf with slightly freshened water. The part of sea inhabitants had died out, others had moved to the entry of this gulf, and some fish species including ancestors of Japanese river horsefish had settled in rivers.
This fish differs from sea neighbours only a little. Japanese river horsefish reaches length about 40 cm from which long flexible tail accounts more than half. Head of this fish is mobile and has long pipe-like snout on which tip the small toothless mouth opens. All fins of this fish are transparent, and river horsefish swims mainly due to wavy movements of back fin.
Japanese river horsefish lives in thickets of underwater plants. This harmless fish eats crustaceans and fry of fishes, and is not able to swim quickly. Therefore main defence of Japanese river horsefish is the ability to masking. The body of fish is colored green with longitudinal yellowish strips. On the body there are some dark irregular-shaped spots.
Colouring of fish is supplemented with the fantastical body shape: from head up to the middle of back the crest of small leaf-looking outgrowths stretches. Near eyes of fish “moustaches”, two long peaked outgrowths doubled at the basis, grow. On sides of fish there are two parallel rows of small outgrowths. When the fish is in danger, it clings by tail to stalks of plants, and rocks according their waving in water.
Not all predators search for catch with the help of sight. Some of them badly see at all, but have sharp sense of smell. Even the most skillful masking does not save from such “pathfinders”. Therefore additionally to ability to hide Japanese river horsefish had developed means of active protection. On its long tail which is able to be bent in any direction, from above, from below and on each side sharp spikes grow. While the fish is not disturbed, they help to cling to plants. But if the fish is seized, it starts to defend. The river horsefish seized by predator is twisted by tail around of the enemy, trying to prick it, and strongly gripes the ring. Such reception may be enough for many local predatory fishes to let this fish off. Even water birds not always can swallow this fish alive: in bird’s throat the river horsefish twists to ring and also starts to rotate tail from side to side, causing strong pain.
Similarly to all sea horses, at this species the leaging role in breeding is played by the male. It bears posterity in brood pouch on stomach, and feeds posterity through blood – blood vessels sprout to each grain of roe in brood pouch, and larvae receive an additional feeding. At this species fertility is rather small: only 50 – 60 eggs. But the posterity hatches very large – the length of newborn river horsefishes reaches 2 – 3 cm. They develop in brood pouch of the male within one month, and begin independent life right after births. Felt the approach of delivery male searches for river bays with slow current overgrown with small-leaved water plants. Here the newborn posterity finds plentiful food like tiny plankton crustaceans, rotifers and large infusorians.

European river pipefish (Neosyngnathus europaeus)
Order: Pipefishes (Syngnathiformes)
Family: Pipefishes and Sea horses (Syngnathidae)
Habitats: eastern Europe, areas in the lower reaches of rivers overgrown with aquatic plants.
In the human era, the basins of the Black, Azov and Caspian Seas were inhabited by black-striped pipefish (Syngnathus abaster). It was remarkable by its ability to tolerate changes in water salinity well, and was found in the Volga, Don and Dnieper reservoirs, spending the entire life cycle in fresh water. The plasticity of its physiology allowed it to survive the disappearance of the inland seas of Eurasia during the Ice Age: residual populations of these fishes survived in lake systems that remained in river basins. Its Neocene descendant – European river pipefish – is already a true freshwater species that inhabits the rivers of eastern Europe. It is a medium-sized fish of a characteristic appearance, up to 15 cm long, with a very elongated body and thin bony shell of movably connected shields. The color of the body is inconspicuous, brown-green: usually on a green background there is a longitudinal brown stripe along each side, but sometimes the fish turns out to be almost completely brown, with a green stripe on the belly. Male has a brood pouch formed of folds of soft skin on his stomach.
Like its ancestor, this species is a very poor swimmer, and prefers to keep in areas with slow currents and abundant thickets of aquatic vegetation. Like its relatives, it is a specialized planktonophagus; the snout is elongated, with a small terminal mouth. Fish feeds exclusively on zooplankton and fry of other fishes, which it catches in the thickets, where they hide from enemies. This species is characterized by low competitiveness, so it is never particularly numerous.
Avoiding competition for food with the young of other fish species, European river pipefish has chosen a special reproduction strategy: enchance of the parental contribution to each of the offspring. Juveniles of this species are not numerous; they develop for a long time in the male’s skin brood pouch. There are only 30-40 eggs in the clutch of this species, but the birth of juveniles spreads out for several months. Some males even overwinter with eggs, continuing thebreeding cycle in the spring. Male’s brood pouch is a real “conveyor” for growing juveniles. Male’s body is able to slow down the development of eggs without weakening their viability, and selectively supply nutrients to only a few embryos that are actively developing at the moment. The male simultaneously develops 2-3 juveniles to a maximum size. After their birth, the development of the next batch of offspring begins. Due to the extended incubation period of the clutch, the male is able to incubate no more than two clutches during his life. Young fishes are able to feed on Daphnia and other large planktonic crustaceans immediately after birth.
Sexual maturity comes at the age of 1 year, in autumn-born fry – in the second year of life. Life expectancy rarely exceeds 3-4 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Cleaning pipefish (Barysyngnathus tonsor)
Order: Pipefishes (Syngnathiformes)
Family: Pipefishes and Sea horses (Syngnathidae)
Habitat: coastal waters in the tropical and subtropical regions of the Indian Ocean, marine and brackish waters.

Picture by Tony Johnes

At the boundary of Holocene and Neocene, mass extinction destroyed the richest fauna of coral reefs. The very complex ecosystem, permeated with many chains of trophic, symbiotic and parasitic relationships, collapsed in the era of anthropogenic pressure, and climatic changes destroyed the remnants of reef communities. The reefs of the Neocene epoch formed almost from zero: new groups of reef builders evolved, and the reef settlers gradually adapted to a new way of life, taking their place in the newly forming ecosystems.
The vacant place of cleaners on the Neocene reefs was occupied by animals, which are often very far from each other in their systematic position. At the reefs of the Pacific Ocean, this role belongs to the grooming crab belonging to the swimming crabs family, and in the Indian Ocean, its “colleague” is cleaning pipefish, a particular representative of pipefishes.
Changing the diet is a complex evolutionary step for pipefishes, which are specialized consumers of small planktonic animals. During the ecological crisis, some species of these fishes switched to the consumption of benthic invertebrates, and among these species a group gradually emerged, whose representatives passed to gathering small animals from bodies of other reef inhabitants.
Cleaning pipefish is a small representative of fishes: the body length of an adult does not exceed 10-12 cm. This fish is very brightly colored: the general body color is bright pink with an orange tint; there are white vertical stripes on it, shaded along the edge with very thin black strokes. Fins of this fish are transparent.
Body of cleaning pipefish is strongly laterally compressed, especially in its front part. The snout is elongated with a movable mouth at the tip; it exceeds a little bit one third of the total length of this fish. Body is shortened, deep and convex on the abdomen. In males bearing offspring, a brood pouch with blood vessels visible under the skin is visible behind the abdomen. Shell plates on the body are thin, arranged in three longitudinal rows on the body and in two rows on the tail stalk. Tail of this fish is thin, with a rounded tail fin. The bases of dorsal and anal fins are muscular; the movements of these fins allow the fish to move back and forth easily.
Jaws of cleaning pipefish are equipped with corneous combs that allow it to scratch the skin of the fish being served, and the snout compressed from the sides makes it easy to penetrate under its gill covers. This fish gathers parasites, cutting them with the corneous edges of its mouth, like with scissors, and sucks them into the mouth.
Unlike most cleaning species, cleaning pipefish is not a territorial and solitary species. Fishes of this species stay at the reefs in a small school in well-lit places where they can be clearly seen from afar. Usually one fish is served by several individuals of cleaning pipefish at once, and in a group they work much faster. In case of danger, fishes hide in the cracks and crevices of the reef.
Features of physiology allow this fish to settle in places where seawater has lower salinity – in estuaries, brackish sea bays and in mangroves. Occasionally, freshwater populations of this species appear in the lower reaches of the rivers of South Asia and Zinj Land, differing in smaller body size, but retaining their bright color.
Both females and males are present in the group. Some of the males are busy with eggs carrying; such individuals behave more cautiously, preferring to serve smaller fish. There are up to 20-30 eggs in the clutch, receiving nutrition from blood vessels sprouting through the skin of the brood pouch. Gestation of offspring lasts about 2 weeks; during this time, the male loses weight, giving part of the accumulated nutrients to the offspring. During the year, the male bears up to 4 broods. Young fishes lead a solitary lifestyle, joining later the established groups of adults.
Sexual maturity of young fish occurs at the age of 9-10 months, and the life expectancy does not exceed 4 years.

Blood-sucking pipefish (Ichthyoculex sanguisugus)
Order: Pipefishes (Syngnathiformes)
Family: Pipefishes and Sea horses (Syngnathidae)
Habitat: reefs in the coastal shallow waters of the Indian Ocean, the coast of the islands of Indonesia.
In the process of evolution, representatives of one or another group of living organisms change in different directions, which are permissible with the initial type of body anatomy of the ancestral form. The process of adaptive radiation is more successful the less specialized the common ancestor of the group. And the biological meaning of this phenomenon is to reduce interspecific competition among the descendants of a common ancestor.
Pipefishes belong to specialized fishes. Their mouth apparatus is highly specialized in consuming small living organisms by suction. However, one of the representatives of this group – blood-sucking pipefish – got an unusual specialization that allowed it to change its food source – it became a blood-sucking parasite. Obviously, the blood-sucking pipefish descends from a certain species related to the cleaning pipefish (Barosyngnathus tonsor), in which a random behavioral feature associated with cleaning the gills of large fish has turned into a feature that promotes survival.
Blood-sucking pipefish has a very small body size – its length is only about 5-6 cm. This fish has a thin long snout, and a sharp outgrowth is developed on the upper jaw, with which it bites through the gills of the host fish. Body of this fish is covered with several longitudinal rows of smooth, tightly fitting bone plates, and is inflexible. This fish swims with the help of dorsal fin movements; tail fin is greatly reduced and is represented by several rays connected by a membrane. A pair of enlarged bone plates on the abdomen forms attachment hooks that can approach each other, enclasping the branchial arch of the host fish.
The coloration of blood-sucking pipefish is pale pink, capable of changing to a brighter one if necessary to disguise.
The eyes are well developed: this fish is able to lead an independent life. Usually the blood-sucking pipefish lives in the branchial cavity of large fish. It attaches to the branchial arch and sucks blood, while inflating so that its stomach filled with blood begins to appear through between the parted plates. The presence of this fish, however, benefits the host fish, since the blood-sucking pipefish also gathers parasitic worms and crustaceans from the gills of the host fish. Occasionally, it leaves the host fish and can survive for some time by attacking small fishes. After the attack of the blood-sucking pipefish, small fishes can die.
This species is a hermaphrodite, but self-fertilization does not occur in the blood-sucking pipefish. A pair of fish that have found each other mutually exchanges their eggs, spawning them into the brooding pouch of a breeding partner. Most often, it happens when fishes swim on the reef, but sometimes two fishes meet each other on the gills of the host fish. There are up to 20 eggs in the clutch, receiving additional nutrition from the blood of the parent. Tiny fry of this species parasitize small fish and often live in branchial cavities of crabs. Sexual maturity in this species comes at the age of 8 months, and life expectancy rarely exceeds 2 years.

Charibda (Ichthyocharibda pelagica)
Order: Pipefishes (Sygnathiformes)
Family: Charibda fishes (Ichthyocharibdidae)
Habitat: sea waters of the Southern hemisphere in areas of temperate and cold climate.

Picture by FanboyPhilosopher

Evolution can be compared to a kind of game, where on par with the rules and regularities the element of chance acts. It is for this reason that among the inhabitants of earth can sometimes appear bizarre and extravagant creatures, adapted, however, to their habitats.
One of these experiments in evolution is the North Atlantic Sea Wyvern (Vivernocampus titan) – a huge fish which is a descendant of the sea horse. In the Southern Hemisphere the whim of evolution has caused the appearance of another being, equally bizarre and distantly related to this species. The cold sea waters of the Southern hemisphere are inhabited by the charibda – a giant pelagic needle-shaped fish reaching the length of 3 meters with a thickness up to 20 cm. Despite its size, this fish is a very poor swimmer and is, in fact, technically plankton.
The charibda slowly drifts in the current, very rarely approaching the coast. Only in severe storms these strange fish are thrown to the shore, where they are helpless and quickly die.
The charibda in appearance resembles a snake, clad in a shell of bone rings. The shell’s scutes, however, are very thin, and on the lower side of the body they are even reduced. The buoyancy of the fish is provided by a fatty liver and a large amount of fat in the body. The unit weight of the fish is almost equal to that of water, and the charibda can easily maneuver in water. But its muscles are very weak and impregnated with fat, so the fish is unable to swim against the current.
The spine of the fish is very flexible, so it can roll up into rings and knots, rubbing on its own body and getting rid of parasites. The tail is a little less than two thirds the length of the fish.
Charibda fins are relatively small in size. The caudal fin is reduced to one short, thick spine. The dorsal fin is fan-shaped, with a strong fleshy base. This is the main propulsion of the fish; making undulating waves of the dorsal fin, the charibda can slowly move through the water column. Broad pectoral fins-also with strong bases-are turning rudders and help the fish keep its balance.
The head of the charibda bears features characteristic to members of the order. The fish has movable large eyes which can be rotated in different directions. The snout is elongated and tubiform, with a small mouth at the end. The opercles form a suction device. Abruptly opening them, the fish can draw in water as well as food organisms.
The charibda feeds exclusively on planktonic organisms: jellyfish, salps, worms, and crustaceans. When feeding the fish sucks them in entirely, hence the name. The gills of young fish form a filter device, allowing them to pump in a large volume of water and suck in clusters of small animals: crustaceans and fish fry. The charibda is immune to the poison of jellyfish and planktonic starfish.
The charibda has a soft colouring: silvery-gray with a greenish tinge; fins are transparent. Males and females do not differ in color.
Charybda reproduction is confined to the spring. Males and females find each other by smell and a male wraps his tail around a female, waiting for her mature eggs. At this time he drives away rivals with his head. The fecundity of this species is very high: up to 150,000 eggs. The female lays her eggs in the male’s brood pouch and does not care for her offspring. The inner surface of the brood pouch is covered with villi; the blood vessels grow through them to the eggs and provide them with extra nutrients.
Juveniles hatch of their eggs after 15-20 days and after another 2 days they leave the brood pouch. The length of the fry at the exit from the pouch is 3 mm. They passively float in the water and only eat prey which is in close proximity to the mouth. A significant part of young fish dies before reaching even the fifth of the length of an adult. Sexual maturity occurs in young fish at the age of 3-4 years; a lifetime is more than 50 years.

Translated by FanboyPhilosopher

Sea vouivre (Thalassovouivre inconspicua)
Order: Pipefishes (Syngnathiformes)
Family: Pelagic seahorses (Pelagocampidae)
Habitat: Atlantic coast of Europe, forests of “underwater trees”.
The mass extinction of marine fauna at the turn of Holocene and Neocene largely affected species that depend on the well-being of ocean plankton – feeding on it or spending part of their life cycle as a part of it. The fauna of the open ocean in the Neocene began to form almost anew, but coastal species mostly survived and continued to evolve, mastering new ecological niches. Because of it, the descendants of seahorses and pipefishes appeared among the fishes of the open ocean. And other species of their relatives developed the lifestyle of coastal predators.
Perennial angiosperms form a kind of “sea forests” off the coast of Europe and North Africa. They harbor many species of fishes and invertebrates, and one of the strangest local predators is a very large seahorse – the sea vouivre, a relative of the sea wyvern. It has increased in size, but has not left the coastal habitats – it is a kind of lateral branch, a relic of the early evolution of pelagic sea wyverns.
This is a fish about 2 meters long, of which about half is a thin flexible tail that lacks the tail fin. Shell rings in the rear third of the tail are equipped with small spines and allow it to grasp the support more firmly. The tail is prehensile, easily bending in any direction and securely fixing the fish on the substrate. Pectoral fins with strong bases are the main organ of movement in the water, but sea vouivre is a non-mbile fish that rarely changes its place of residence. A swimming fish flaps its pectoral fins like wings. Dorsal and anal fins are reduced.
A notable feature of the appearance of the fish is a set of long leaf-shaped skin outgrowths. One row of them stretches from the crown along the entire spine almost to the tail tip. These outgrowths can branch out. Two rows of lobe-shaped outgrowths stretch along the sides. Two rows of lobe-shaped “sideburns” grow on the head – from the tip of the snout along the entire head and above the eyes. The eyes themselves are large, convex and mobile. The elongated snout ends with a small terminal mouth; on the lower jaw, there is a “beard” of several thin sensitive outgrowths. Touching them by small animals causes an instant reaction of suction of prey.
Male and female almost do not differ from each other: the female is only slightly longer, and the male has a developed brood pouch on his stomach. The coloration of fish of both sexes is inconspicuous: a combination of greenish, yellowish and brown shades. Usually the body has a brown color, and the color of the outgrowths varies from green to yellow. In case of stress or irritation, the fish turns completely black.
Protective adaptations of this species are sophisticated camouflage, armor of bone plates and also brown poisonous liquid released in case of danger.
Sea vouivre is an ambush hunter waiting for small prey in the thickets of plants and sucking it whole. The diet of this species includes small fish and crustaceans, sea worms and other animals that this fish is able to suck in with its mouth. Long snout allows sea vouivre to get prey from its shelters – burrows, vegetation and crevices between rocks.
The method of reproduction of this species is traditional for seahorses – the male bears non-numerous eggs in its brooding pouch. After a primitive courtship ritual involving a grotesque slow-motion chase of males after a female, fishes attach their tails to the substrate, and the males try to push each other away from the female. The best of the males receives from the female 30-50 large eggs in its brooding pouch. Its blood vessels penetrate into the epithelium of the inner side of the pouch, and supply the eggs with oxygen.
Fry are relatively large, up to 50 mm long. They are translucent, covered with small outgrowths, and immediately after leaving the brooding pouch, they begin to hunt small animals. Some of them even keep for the first time among the outgrowths on the male’s body, where they successfully hunt small marine animals. Sexual maturity comes at the age of 5-6 years; life expectancy is up to 35-40 years.

Glass false angelfish (Pseudophyllum crystallinus)
Order: Percoid fishes (Perciformes)
Family: Snooks (Centropomidae)
Habitat: down flow of Zinj Land rivers, thickets of underwater and coastal plants.
Mangrove thickets are the special inhabitancy – here inhabitants of sea and freshwater inhabitants meet. Fluctuations of salinity and water level create the certain difficulties for live creatures adapted to constant parameters of inhabitancy. But the part of mangrove thickets inhabitants has adapted to endure changes of water salinity and prospers in changeable world of mangrove woods. Among fishes inhabiting these places there are gluttonous predators and peaceful omnivorous fishes. Some inhabitants of mangrove thickets have adapted to endure inflows and outflows and live in mangrove woods constantly; other species come into this biotope only temporarily.
At the distant border mangrove woods where influence of ocean is felt only till the highest inflow the vegetation is more similar to river one. Here the bottom is covered with thickets of underwater grassy plants, and at the coast rich bushes of high marsh grasses grow – reed reaching height of three meters and more. Among stalks of reed the set of insect larvae lives and on plants bryozoans and hydroid polyps sit – they are recent fugitives from the sea. That minimal salinity of water which turns out at mixing tidal waves with the water of the river quite suffices to them.
The set of small animals involves in these places one surprising fish, the descendant of glassfishes (Chanda), characteristic inhabitants of brackish waters. This fish is a high-bodied predator of lower reaches of rivers and mangrove thickets. This fish is a little similar to angelfishes (Pterophyllum) belong to cichlids family (Cichlidae) known to people. Similarity of habit of life had made these fishes very similar to each other.
Body of glass false angelfish is very deep (20 cm and more at length about 15 cm) and transparent – this feature is inherited from the glassfish. Interiors of fish are opaque, but they are disguised by shining film of peritoneum. Eyes of false angelfish are big and silvery.
Living among rich thickets of reed, this fish has short body. But unpaired fins of this species are very high. In back fin sharp poisonous spikes grow. The membrane between them is strongly reduced, therefore prickly fin rays may move freely. In anal fin first three rays are also prickly. It is the only active protection of this fragile looking fish. Abdominal fins of false angelfish are long – their tips reach top of anal fin. They consist of two thicken rays and serve for balance maintenance. On the second ray of these fins tiny sharp spikes located in some lines are advanced. With their help fish clings to stalks of plants for better resisting to strong tidal wave or current till the high water. At danger glass false angelfish freezes among reed stalks and on the body of fish grey vertical strips appear. In skin of fish there are chromatophores which are contracted in rest. At irritation or excitation of fish they open, giving to fish striped colouring.
False angelfish eats tiny animals – swimming larvae of mosquitoes, larvae of water beetles, worms. Its mouth is small but it can protract forward as a tube. When it is protracting, the current of water inside of mouth appears – this way the fish sucks in small swimming animals. Teeth are tiny and bristle-like – they serve for tearing off attaching catch from substratum. In fresh reservoirs false angelfish breaks from plants hydras, in brackish water of river mouthes it eats tentacles of hydroid polyps living here. This fish is tolerant to their poison.
This fish spawns in river estuaries choosing shallow gulfs with quiet and slightly brackish water. Eggs at these fishes are looked after by male which is larger, rather than female. The spawning may repeat up to 4 times in succession within half-year, and then male has a rest. In courtship dress it becomes striped, and edges of high unpaired fins get blue color. The courting male “dances” around the female, touching it by tips of abdominal fins. The female ready to spawning turns almost completely transparent and inclines the body on one side, showing to the male the belly as a sign of submission. The female pastes very small eggs on stalks and leaves of plants preliminary cleared by male, and at once leaves nest. Male stays to care for posterity: it fans eggs with fins and clears of dust. If necessary the male drives off other fishes having too closely swam to eggs. When larvae start to swim, male leaves the post. Larva of glass false angelfish is very small. It passively soars in water and eats plankton animal – rotifers and large infusorians. The significant amount of larvae perishes: larvae of advanced age become active hunters and eat smaller fry. At monthly larvae unpaired fins start to increase, and the body gets the shape characteristic for adult fishes. At the age of about half-year young false angelfish reaches length 6 – 8 cm, and one-year-old fish begins able to spawn.

Giant glassfish (Megachanda pellucida)
Order: Percoid fishes (Perciformes)
Family: Snooks (Centropomidae)
Habitat: Tanganyika passage, thickets of seaweed in coastal zone.
Coastal waters of Tanganyika passage, slightly freshened by river waters, are fine place for life of numerous fishes. Far away from river mouthes where salinity of water is only a little below normal sea one, the bottom is covered with rich thickets of seaweed of various shapes. Among them there are species similar to palm leaves, fans, grape bunches and clusters of mushrooms. In this seaweed various species of small fishes, crabs and shrimps find shelter and food, and, in turn, predators, settling here, eat them. One of largest predators in underwater thickets is giant glassfish.
In Holocene many various species of glassfishes inhabited fresh and brackish waters of African and Asian coasts of Indian Ocean. But these species usually did not exceed 5 – 10 cm in length, and the species 18 cm long could be considered among them as the giant. But it would look a crumb near to one of Neocenic relatives, the giant glassfish, strange fish about 80 cm long.
Continuing “family tradition”, This fish species have kept a transparency characteristic for glassfishes: through its skin the skeleton is perfectly looked, and interiors are disguised from curious sight by silvery opaque film of peritoneum. But the constitution was made as a sacrifice of body transparency: body of fish is very deep and thin: at length 80 cm thickness of body is only 3 - 4 cm. The transparency of body helps this fish to mask among seaweed from catch and probable predators. For protection against attack of other fishes in back and anal fins of this fish strong poisonous spikes stick up.
At this fish, similarly to its Holocene relatives, there is very large head with big extensible mouth. When the giant glassfish attacks prey, its mouth extends like a tube and soaks up fish or other small animal.
Habitats of giant glassfishes are thickets of seaweed at the depth from 2 up to 10 meters in rather well warmed up shallow sites. Usually these fishes hide among seaweed and wait, while possible catch will come nearer to distance of successful throw. If it is a little of catch, fish can search for it itself. Favorite forage of giant glassfishes is shrimps and small fishes. When the perch is in an ambush, it is very difficult to find it out: its body is very high and transparent; therefore it is almost not distinguishing on the background of waving seaweed.
But except for advantages thin high body creates problems: when storm rages, it is difficult for such fishes to resist to disaster. Therefore giant glassfishes differ in good ability to weather forecasting: instinctively feeling approach of storm, fishes search for shelter. Usually before storm schools of these fishes leave seaweed and swim down to the deepest places of coast – to underwater canyons and caves, and also in cracks of rocks, where it is possible to hide from breaker impacts.
Giant glassfishes breed similarly to ancestors, in brackish water of coastal bays and river mouths. At these fishes spawning is paired: male finds a bush of water plant, clears its leaves and adjoining territory of dust, and then starts to involve female. To time of spawning it has a wide silvery-blue strip on soft back fin. When near to bush female appears, male swims up to it and starts to push her by side to the plant prepared for spawning. If female is ready to breeding, she responds on courtships of the male. The generated pair some time in common cleans bush and patrols its vicinities, driving neighbours away. After that, when eggs at the female will ripe, spawning begins. Female spawns eggs (about 50 thousand small grains of roe) on leaves of plant and at once leaves it. Male fertilizes eggs and protects them within one week – up to fry hatching. When posterity hatches and starts to swim, male abandons it, and fry appear leaved to their own. Within first two weeks of life their life is rather passive: young perches soar in thickness of water and eat plankton which appears literally “right under their very nose”. But then they turn in active predators, devouring even their own smaller neighbours. At one-year-old age young perches grow up to length of 5 cm. But in three years they already reach length of half meter and become sexual matured. Life expectancy of this species is up to 8 – 11 years.

Giant monster perch (Deinolates vorax)
Order: Percoid fishes (Perciformes)
Family: Snooks (Centropomidae)
Habitat: Tanganyika passage, mangrove thickets and stony areas near coast.

Picture by Amplion, colorization by Biolog

In XX century of human era to the African Victoria Lake the giant Nile perch (Lates niloticus) had been introduced; and later it had practically completely exterminated populations of local species of cichlids. Probably, such thoughtless step from the part of man has given to this species of predatory fishes an every prospect of survival in the future. When Great African lakes had turned to sea gulf, and later to passage, the new species of predators, giant monster perch, the lineal descendant the giant Nile perch, had occupied shore mangrove thickets. Great African lakes in which this species evolved, are in equatorial zone of Earth, therefore this representative of heat-loving fishes had managed to survive.
This fish is huge solitary predator of sea and brackish waters, the original analogue of sea groupers. The length of body of giant monster perch reaches 2 – 2.5 meters at weight up to 200 kgs.
During inflow the wide zone of mangrove thickets, especially plentiful on east coast of Tanganyika passage turns to circuit of small islands. Marsh and overland inhabitants of these places hide in holes or get on trees, and sea fishes visit in these places for feeding. Schools of fishes move in passages between trees, gathering insects fallen in water. But they can become food for one of the most gluttonous local predators.
Fish looking like rotten stump of tree trunk waits for nothing suspecting small fishes in shadow of mangrove roots. Its scale is spotted with pattern of longitudinal twisting strips giving similarity to bark, and on head small skinny outgrowths, masking eyes and nostrils, grow. When any small fish swims up too close, instantly wide mouth opens, and it is literally tightened to teeth of predator by stream of water. Throw happens so fast, that only cloud of silt and some fallen leaves twirling in water show that here something had taken place. Having swallowed catch, fish freezes again, having folded fins. If the sunlight, having appeared through foliage, falls on body of predator, fish moves in shadow and continues patient expectation.
It is the giant monster perch, one of most gluttonous predators of Tanganyika passage. During outflow the fish quickens a little: continuing expectation, it is possible sometimes to appear in shallow water. Huge fish emerges from bottom and then it can be examined in more detail.
At giant monster perch there is massive head with wide mouth oblique upwards. On jaws numerous small sharp teeth grow. Small eyes of fish are shifted to the top third of head, and are disguised by skinny outgrowths “eyebrows” similar to seaweed. The first back fin of fish is high, triangular; spikes strongly jut out from its membrane. Two-lobed tail fin of giant monster perch is wide and rather short. The body is deep, short and compressed from sides: it permits a fish to maneuver between roots of mangrove trees: in mangrove thickets the maneuverability is more important than high speed.
Colouring of giant monster perch helps fish to mask among roots and trunks: body is colored soft brown with plenty of twisting dark longitudinal stripes, and only bottom part of stomach has silvery shine. Cryptic colouring is supplemented with plenty of outgrowths on head of fish: along head a line of knob-looking outgrowths passes, under eyes and in corners of mouth also there are some skin warts giving to fish strange and fantastical appearance.
The giant monster perch lives in water of varying salinity, normally feeling like both in sea, and in fresh water. The fish spends the most part of time, having half dug in sand. Then because of colouring and shape it is easily possible to mix it up with rotten tree trunk, and small fishes swim up to predator to the certain death, deceived by its shape.
This species spawns in fresh water, making migrations to river estuaries. In spawning season courtship dress of males becomes brighter: brown background is replaced by copper-red, and strips become narrower. At females the stomach considerably brightens, showing thus readiness of these fishes for spawning. Males and females swim up in rivers by common schools, but males quickly leave school and search for places for spawning.
The giant monster perch spawns eggs on roots of trees washed away by water, or on bushes of small-leaved plants. Being found suitable place, male starts to invite swimming near it females to spawning. He opens pectoral and abdominal fins forming as though “collar” around of his head, and utters sounds similar to growling and bark. When one of females shows intention to spawn, pair clears together the substratum chosen by male, and drives off from it all neighbours. Spawning occurs in the evening, then female leaves the river, and male protects eggs up to fry hatching. In clutch of giant monster perch can be up to 200 thousand of small transparent grains of roe.
Fry of giant monster perch is very small, and their big part perishes from every possible predator already at first days of life. But survived individuals have an every prospect to survive: they feed with every possible river plankton, and do not squeamish with their own neighbours, being behind in growth. At this time colouring of fishes is cross-striped – black strips on silvery background. In due time strips break off to irregular-shaped spots which to the moment of migration from rivers merge in longitudinal strips, characteristic for adult fishes. The background also changes from silvery to dark one. Young fishes live the first half-year of life in the river, but then, having reached size about 10 cm, gradually start to migrate to zone of mangrove thickets. Here young fishes should face real danger second time in life: mangrove thickets are occupied by adult fishes which will not suffer competitors, and can simply to have eaten small fishes of the species. Therefore young giant monster perches search shelter in those places where adult fishes can not squeeze through.
The part of young fishes can stay to live in rivers for ever, forming small sedentary form reaching length about 1 meter. Such fishes usually can not compete to larger neighbours, evolved in sea, and spawn upstream, or at shallow sites of rivers. But their posterity is quite viable, and in good conditions reaches the usual size for this species.
At the age of five years at length of body about meter, these fishes become mature. The lifespan of giant monster perch may reach 40 years.

European sunfish (Neolepomis neolepomis)
Order: Percoid fishes (Perciformes)
Family: Sunfishes (Centrachidae)
Habitats: Central and Southern Europe, the Balkans, overgrown areas of rivers.
The pumpkinseed (Lepomis gibbosus) was one of the many fish species acclimatized in Europe during the human era. In the historical era, it quickly spread across European reservoirs, and began to compete with native species. Its Neocene descendant – European sunfish – inhabits calm and abundantly overgrown with aquatic vegetation fresh reservoirs, having inherited from its ancestor a relative thermophilicity. This species displaced the descendants of European perch (Perca fluviatilis) from the rivers of Europe further north. The maximum length of individuals of this species is 20 cm with a weight of up to 500 grams. The body is rounded, compressed from the sides, slightly lower and elongated compared to the ancestor. The coloration is relatively bright – green with orange mottling. Back is brown; lower part of the body and belly are yellowish. The characteristic “ears” with ocular spots are preserved on the operculi. Actually, the eyes of this fish, as a rule, are masked by mottling.
It is an exclusively zoophagous fish, feeding on juvenile fish, aquatic invertebrates and ones that have fallen into the water. Usually European sunfish ambushes among water plants behind rocks. During the spawning season, the male builds a nest of sand and small stones to attract the female, which spawns a small number of large eggs. Attracting the female to his territory, the male utters loud chirping sounds, and his coloration becomes very contrasting: the green background pales, and the orange spots turn brown. A small fatty growth appears on the male’s head in a courtship dress, like in cichlids. Competing males can fight each other by striking with this outgrowth. There are up to 200 large eggs in the clutch. After spawning, the male quickly changes his coloration to normal one, and drives the female away. He stays constantly at the nest, ventilates the eggs with the movements of his fins, and protects the offspring until the juveniles begin to swim independently.
Young fishes reach sexual maturity in the second year of life, but active growth continues until the age of 5-6. Life expectancy does not exceed 30 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Musical croaker (Musisciaena cacophonica)
Order: Percoid fishes (Perciformes), suborder Percoidei
Family: Croakers (Sciaenidae)
Habitat: rivers of Western Africa.
Croakers managed to survive the “plankton catastrophe” at the boundary of Holocene and Neocene due to their attachment to benthic habitats and the ability to survive in fresh water. Some of the species of these fishes have become extinct – mainly it affected tropical forms associated with coral reefs. However, the surviving species recovered their numbers rather soon and the evolution of these fishes continued.
In the Neocene, croakers are very characteristic fish species in the rivers of the tropical and subtropical zone. One of their species lives in the rivers of West Africa – the musical croaker, one of the loudest-voiced inhabitants of this area.
Musical croaker is a medium-sized fish – the length of an adult is about 25-30 cm. The body of this fish is elongated with a sharp rise immediately behind the head and gradually tapering to the tail. There are 7 spines in the spiny part of the dorsal fin; the very first one is longer than the others. The soft part of the dorsal fin is low; it stretches along the entire back to the beginning of the tail stalk. Tail fin is trapezoidal with a slightly concave posterior margin.
The mouth of this fish is inferior, wide and non-retractable. There is one short fleshy wattle on the lower jaw, which is used to search for prey at the bottom.
Musical croaker is a schooling fish and keeps in schools numbering up to 200 individuals and more. The coloration of this fish is very characteristic of schooling fish. The general color of its body is bluish-white with a pattern of narrow dark gray longitudinal stripes. Large black spots are scattered across the striped background, so the pattern of the fish vaguely resembles a musical notation. The fins are colorless, but dorsal and anal fins have one round black spot in the posterior part, like on the body. This species has large eyes; stripes extend across the iris, continuing the stripes on the body. Thus, the fish’s eyes turn out to be very well camouflaged. Due to this coloring, the contours of separate individuals are lost against the general background of the fish school, which makes it difficult to hunt these fishes.
Musical croaker feeds on benthic animals – shrimps, small crabs and young fishes. This fish keeps in the lower and middle layers of water, near thickets of plants with floating leaves, rarely emerging to the surface. During feeding, a school of these fishes disperses over a large area, but when frightened, it quickly gathers into a spherical cluster in the water column, which is in constant motion. The signal to gather to the school is a loud alarming sound, resembling a crackle. Upon hearing it, all the fishes stop feeding and gather in a school, simultaneously repeating the alarm signal.
Croakers are fishes known for their ability to make sounds. This ability has found a peculiar application in the musical croaker: fishes use sound to protect themselves from the enemy. In case of danger, fishes gather in a school and make a strong noise disorienting the predator. The sounds uttered by each individual fish resemble a rumble, and the sound of a whole school of fish can be heard even on the riverbank. Transmitted through water and bones, the sound of the fish school scares even waterfowl and wading birds appeared to be near the school.
Musical croaker spawns in the sea. Schools of these fishes run to the sea at night and gather in shoals numbering thousands of fishes. The courtship song of this species resembles a lilting hum of the wind. At the beginning of spawning, fishes in the shoal “sing” inconsistently, but by the time the eggs are spawned, their voices sound almost in unison. Each female spawns up to 50 thousand pelagic eggs. Larvae live in the water column for a week, but later settle to the bottom and turns into a fry. The juvenile coloration of this species is black or dark brown. With age, a longitudinal stripe appears on the body, the background color lightens, and the black zones divid into separate spots. One-year-old fishes migrate from the sea to the rivers.
Sexual maturity occurs at the age of 3 years, and life expectancy reaches 20 years.

Sculpin ruffe (Cottocephalus cottocephalus)
Order: Percoid fishes (Perciformes)
Family: Perches (Percidae)
Habitat: Europe, flowing reservoirs with sandy or rocky bottoms.
In the human era, in European rivers the role of small benthic predator was occupied by sculpins (Cottus). However, these fishes were demanding of water quality, and suffered from human activity, and the warming of the climate that followed the ice age that ended the human era finally destroyed the few relict populations of their descendants in the ecosystems of Europe. Eventually, in Neocene, their place is taken by another fish – a sculpin ruffe – a descendant of Eurasian ruffe (Gymnocephalus cernuus). It is a medium-sized fish, the maximum length of which does not exceed 20 cm, and weight is up to 100 g. In its appearance, it resembles typical sculpins, as well as asprete (Romanichtys valsanicola) of the human era. It has a rather narrow, flattened body, a large flattened head with bulging eyes, long and wide pectoral fins, a fairly deep (although lower than at the ancestor) dorsal fin separated into spiny and soft parts. Pelvic fins are narrow and shifted to the chest. The anal fin is lower and longer than that of the ancestor. The spikes of the dorsal fin produce a weak poison with a strong irritating effect – a protective adaptation against predators.
The body color is brown; throat and belly are yellowish-white. Back is covered with dark spots; dorsal and tail fins are also spotted against the transparent background. The rough scales are covered with a slime layer.
This species has kept the diet of its ancestor – sculpin ruffe is zoophagous and feeds mainly on benthic invertebrates, as well as fish eggs and fry. This fish is a typical ambush predator, preferring areas of rivers with shelters – large stones, driftwood or thickets of plants. The fish usually stays on the bottom, and catches prey in one short rush, after which it quickly returns to the shelter. It is reluctant to leave inhabited places, swims in the lower layers of water, and does not like to stay in the open.
Spawning begins relatively late – in late spring or early summer, when the water in the rivers warms up. A pair of fishes spawns a large amount of small sticky eggs (up to 50 thousand ones) into thickets of water mosses or other thin-stemmed plants, where the eggs are well supplied with oxygen, and it will not be carried away by the current. This species lacks any parental care and leaves the clutch immediately after spawning. In the first years of life, a significant part of the offspring dies, including as a result of predation of adults, who act as regulators of the population number. This species grows slowly; sexual maturity comes in the fourth year of life. Life expectancy rarely exceeds 10 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Great songperch (Percantor musicalis)
Order: Percoid fishes (Perciformes)
Family: Grunters (Teraponidae)
Habitat: Arafura Lake.
Grunters (Teraponidae), the family of euryhaline percoid fishes, were characteristic representatives of Australian and New Guinean ichthyofauna in human epoch. Some of them rose for feeding in upper courses of rivers, but migrated to estuaries and the sea coast for spawning. When New Guinea and Australia had merged to unite Meganesia continent, populations of these fishes appeared isolated in two lakes – older and almost fresh-water Carpentaria lake and younger brackish-water Arafura lake which is separated from ocean by extensive areas of mangrove forests. Some species of fishes had left these reservoirs at the stage of their formation, others had died out at decreasing of water salinity, and one more part of species had managed to adapt to new conditions of inhabiting. Among fishes had achieved success, grunters were formed lot of species in these lakes. In courtship season these species fill lakes with “songs” which are audible sometimes even above the surface of water.
Grunters are pelagophils – they spawn a plenty of tiny eggs which are a little bit denser, rather than water. Living in common, different species of these fishes could easily hybridize at joint spawning. The necessity to distinguish the congeners has resulted in occurrence during the evolution of the “songs” sharply differing in sounding at related species of these fishes. Representatives of the same genus of these fishes, songperches, represent an example of ethological isolation of the species living in same place. Some species, similar externally, but differing by ecology, size and some elements of colouring, live in Arafura Lake. However, the sharpest distinctions between these species are shown during the courtship “concerts” which serve for gathering of representatives of the species and synchronization of their biological rhythms. The necessity of recognizing of congeners is closely connected to the choice of spawning places: all songperches use for spawning sites of lake far from river mouths, where there is constant salinity of water and depth is no more 10 – 15 meters.
The most typical species in this group is great songperch inhabiting coastal biotops of lake along the edge of mangrove forests and thickets of pandanus. At the border of two habitats schools of fishes of this species find a plenty of food – small shrimps, worms and snails.
Great songperch is rather large fish: the length of its body reaches half meter, and weight of adult individual is about 5 kg. It has deep body compressed from sides allowing such large fish to penetrate easily deep into mangrove thickets. Head of this fish has wedge-like shape, and rather small mouth can extend forward, allowing gathering of small animals from surface of mangrove roots. Eyes are shifted upwards and are located on border of last third of head.
Colouring of this species is modest enough: slight greenish shade on silvery scale without strips. Contrast black spots are located on head (forehead and area around of eyes) and on tail (vertical strip at the back edge of tail fin and stripe on tail stalk). Unpaired fins are transparent; spiny part of back fin differs in lengthened fin rays. Pricks of spines growing in first back fin and in anal fin are very painful.
Schools of these fishes total up to hundred fishes, and in courtship season they gather in many thousands shoals. Fishes distinguish relatives using sounds uttered by them. Because closely related species of songperches utter different sounds, fishes correctly distinguish congeners and join them. Mistakes happen at night more often when fishes are not so active and do not utter sounds. But in the morning the stranger, having caught a voice of another species, at once leaves the school – otherwise its voice causes aggressive behaviour in fishes of another species, and it may be strongly bitten or will receive some ramming impacts by head. Having gathered in numerous school, songperches stop feeding and spend a significant part of time for loud synchronous “singing”. Such sound sets original rate to biological rhythms of fishes, and synchronizes their readiness for spawning. Night before spawning passes noisily: fishes continue uttering of sounds even in darkness, and keep activity (and one of species even day time colouring). In the morning rough spawning begins, and females spawn a plenty of eggs – up to 100 thousand small grains of roe. Males fertilize eggs, and the school of fishes swims to depth. The care of posterity at this species is absent. After spawning number of school does not stay constant: former congestions separate, and in the same school after spawning fishes from five and more schools existed before spawning may swim.
The larva hatches approximately in 36 hours. The first days of life it soars in water and eats nanoplankton. At the age of one week gradual transformation into fry begins. Juvenile colouring of songperches is cross-striped; when they grow, strips on the body turn pale and vanish, only marks on head and tail are kept. At one-year-old age fishes reach about one third of length of adult individual, and at the age of three years they take part in breeding. Life expectancy of great songperch and other large species reaches 20 years; small species are mature in 1 year age and live no more than 10 years.
Some other species of songperches live in Arafura Lake:
Chime songperch (Percantor resonator) is schooling fish up to 30 cm long. Voice of this species may be easily recognized – it represents single musical sounds of low tone resembling tolls. Colouring of body of this species is silvery-blue; on head there is a wide area of black color, including lateral parts of head, forehead and the bases of operculums. The tip of muzzle, lips, lower jaw and edges of operculums have the same colouring, as body. Also the tail fin of this species has black colouring with colorless border. The present species lives in schools numbering up to 200 – 300 individuals and keeps far from the coast. These fishes eat small pelagic invertebrates and fry of other species of fishes.
Sparrow, or twittering songperch (Percantor passerinus) is the smallest species of the genus: the length of adult individual does not exceed 15 cm. Body of this species is rather short; head has high forehead with the fat pillow stretching to the beginning of back fin. Its courtship song represents short series of chirping sounds of high frequency similar to twittering of small bird. The fish is colored very attractively: body has a distinct greenish-blue shade, eyes are surrounded by dark spots, making an impression of “glasses”, and on back part of body and tail there are thin vertical strips. In courtship season these strips almost disappear, but the tail stalk is colored black. Twittering songperches almost constantly live in mangrove thickets and eat small fishes and shrimps.
Cricket songperch (Percantor aquagryllus), a fish about 20 cm long, has more prolonged body, rather than other species of genus. It has golden colouring of body, and on head and forward part of body it has black saddle-shaped spot stretching from back edge of eye up to the end of first third of spiny back fin. This spot stretches down to the basis of pectoral fins. On tail stalk there is also small saddle-shaped spot of black color. In courtship season this fish utters long series of clicks similar to chirring of cricket. Schools of the present species, numbering over hundred of individuals, keep in mouths of rivers and frequently rise in middle watercourse, but return to the lake for spawning. This species is a predator and eats small fishes and shrimps, hunting them in top layers of water and especially in thickets of floating plants.
Glass-clincking songperch (Percantor crystallinus) is named not for appearance at all. It is a fish of coal-black color with silver-gray forehead and sides of head; fins are transparent, only their bases have black color. It is the only species of genus, so sharply differing by colouring from other songperches. But such colouring is characteristic for fishes of this species in daytime. At night it becomes pale grey with five vertical strips on body and white head. The length of body reaches 25 – 30 cm. The characteristic voice of this fish is similar to melodious ringing of vineglass which is repeated in long series. Glass-clincking songperch lives in mangrove thickets, eats small fishes and gathers in schools numbering of some tens of individuals.
Sawyer songperch (Percantor serrator) is easily distinguished in courtship season because of long series of abrupt sounds similar to sound of a saw. It is medium-sized species, about 30 cm long. Colouring of body is silvery with bluish shade. Snout and lower jaw are black; on the back end of body there is thin vertical strip stretching from soft part of back fin up to back edge of anal fin. Tail stalk and back edges of back and anal fins have some small dark spots. This fish gathers in schools numbering no more of fifty of individuals, and eats benthic invertebrates and small fishes. The present species frequently swims to mouths of rivers and gathers at the border of thickets of aquatic plants, searching for larvae of insects.
Barking songperch (Percantor latraris) is one of the small species of genus: length of adult individual is no more than 18 cm. This species lives mainly in more freshened eastern part of lake where influence of inflow is less felt, and inhabits thickets of pandanus and reed. Separate schools of this species come into the western part of Arafura Lake, but prefer to keep in river mouths. This species has the characteristic deep body compressed from sides and double strips on head: one strip stretches across the tip of snout, and another one lasts across the eye. From the beginning of a back fin frequently one more strip stretches downwards, but more often it does not reach even the basis of pectoral fins. On tail stalk dark spots appear only on occassion. The basic colouring of body is silvery with slight lilacky shade appreciable only at bright light. The courtship song represents the loud abrupt sounds similar to bark of small dog. Mouth of barking songperch is small: this species eats mainly small invertebrates inhabiting thickets of aquatic plants. This species gathers in small schools numbering of some tens of individuals.

Eyre Herring-Grunter (Arripiterapon eyrensis)
Order: Percoid fishes (Perciformes)
Family: Grunters (Teraponidae)
Habitat: Open waters of Eyre Gulf, southern Meganesia.
With the extinction of many common saltwater fish, during the late Holocene “plankton crisis”, new niches became open in the Neocene to the more unpretentious survivors, such as grunters (Teraponidae)
Eyre Herring Grunter is a mid-sized fish, reaching about 30 centimetres long. It differs from its ancestor in more hydrodynamic shape of body and fins, caudal fin is forked and pointed, and anal fin is triangular in shape. The dorsal fin is usually kept flat against the back, forming a small fan shape with large spines, pectoral and pelvic fins are smaller and sub-triangular. Colour is a dull blue-grey, but with prominent silvery sheen appreciable at a distance. Mouth is middle-sized and lined with a single row of small, sharp teeth.
This is a fish that forms large shoals, which move in a united way to feed in groups of smaller fish, fish fry, and crustaceans. Shoals may number up to many hundreds of individuals, even a thousand; they hunt both in the water column and among growths of weed and seagrass. Groups are obvious underwater by their silver mirror-like colour and communicative noises, sharp clicks and grunts from which its ancestor got its name. The silver shining of this species, in its large shoals, acts to disorient predators and make it hard to select an individual.
Sexual maturity is reached at 3 years, spawning takes place in the wet season, fecundity of the female depends on size and maturity, but as many as 100,000 eggs may be laid by each female. Eggs and larvae are planktonic and may drift within the gulf or further out to sea, when larvae mature into small juveniles (5 to 7 cm) they begin to form nursery shoals and congregate in the gulf. Lifespan is up to 10 years.
A related species exists in the oceanic waters of Southern and South-eastern Meganesia, the Southern Herring Grunter (Arripiterapon australis), it differs from its relative in being more adapted to a constant salinity and oxygen level, and they do not venture into Eyre Gulf. They are also about a quarter larger, and their body is more bluish in colour, they spawn in coastal waters.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Caravel fish (Scaphoichthys caravella)
Order: Percoid fishes (Perciformes)
Family: Serranids (Serranidae)
Habitat: Indian ocean, from tropics up to moderately cold areas.
After extinction of whalebone whales and “planktonic accident” caused by global changes of climate at the boundary of Holocene and Neocene ecological niches of pelagic animals turned free that time were occupied with descendants of coastal fishes. Survived small species of groupers passed to large dimensional class; their huge mouth allowed grasping small fishes and cephalopods in a plenty at once. Transition from benthonic to pelagic way of life took place at fishes of various groups repeatedly: already in human epoch the pelagic manta ray (Manta birostris) was known, though its relatives are benthic fishes. In Neocene other inhabitants of thickness of water had appeared; among them the caravel fish, large (body length up to 4 – 6 meters) fish, the descendant of one of Holocene species of groupers, is one of the most unusual species.
Caravel fish has more extended and streamline body in comparison with an ancestor, with powerful tail that allows it to make fast throws. The head with huge mouth makes about 1/4 of general body lengths. Prickly part of back fin at this species is increased and represents a kind of “sail” up to 2 – 2.5 m high, with rounded top edge. “Sail” has contrast colouring of black cross strips and concentric “oculate” spot in back part on brightly shining silvery background. It is used in order to drive prey in dense shoal from which it is easier to eat. Also demonstration of “sail” allows to disorient predators: sharply stretching fin, fish seems larger, rather than actually, and the oculate spot distracts attention of attacking predator from the vital body parts of fish. Colouring of back of this species is steel-blue; belly and sides are silvery.
This fish is good swimmer though in speed it concedes to sharks and to anothers fast swimming pelagic fishes. Similarly to tunas and some sharks of Holocene epoch, like mako shark and great white shark, caravel fish is capable to maintain temperature of body some degrees higher above suroundinf environment due to intensive work of muscles that allows it to feed both in warm, and in cold, but rich in food waters. It has deep forked tail fin, rigid front rays of anal fin; and narrow belly fins are shifted under the bases of pectoral ones and can nestle against the body, being hidden in special longitudinal plica of skin on stomach.
This species lives in top layers of water of Indian Ocean and dives for prey to depths no more then 50 – 60 m. Caravel fish is settled from tropical and equatorial zone almost up to the coast of Antarctica. In the south it may be met mainly in summer when water is warmer. For spawning these fishes migrate to coast of islands of Indonesia, to coastal reeves. Adult individuals live in groups of 3 – 6 individuals. The structure of each group always includes one male, and other individuals are females. It is connected to feature inherited by caravel fish from the ancestor: the gender at these fishes is not fixed genetically and can vary many times in ontogenesis. A dominant individual in group becomes a male. If male leaves school or perishes, his place becomes occupied by alpha female which turns to full-grown male in some weeks.
Caravel fishes eat small schooling fishes and squids, and in waters of Antarctic Region they feed on numerous species of pelagic crustaceans – “the red robber” (Gregariomyzis planctophagus). Hunting individuals surround a shoal of prey and swim around it, lifting and lowering back fins. Thus they drive prey in dense sphere and do not allow it to escape. Periodically one of individuals rushes into congestion of prey, and like huge vacuum cleaner, sucks it in with water. Then water flows out through gills, and the food is filtered by branchial stamens and is swallowed.
The courtship period at this species is strongly dragged out – at the coastal reeves schools of caravel fishes may be met at any time of year. But especially intensive courtship games take place in winter when schools of fattened fishes return from Antarctic waters. In courtship period the back fin of males is colored bright golden, and colouring of body becomes more contrast and intensive. Spawning occurs near to coral reeves during the day time inflow. At this time schools of many tens large fishes approach to the coast. Males, appearing near each other, begin demonstrations of force to each other. They open back fins and try to push each other aside from the chosen site of reef. Frequently stronger male pushes the contender almost half out from water. At this time above water numerous brightly colored back fins of males rise, which the more modestly colored fins of females join.
Spawning takes place above sandy sites at the bottom. Each female spawns huge amount of tiny eggs – up to 40 – 50 million grains of roe, packed in dense slime cords. Male fertilizes eggs and they begin to inflate, absorbing surrounding water. At this time some sites of reef become covered entirely by jellylike paste of eggs under which crabs, shrimps and tiny fishes are trapped. Eggs develop within two days, and tiny helpless young ones leave them. Young caravel fishes live at the reef, like groupers of Holocene epoch, eating small fishes and invertebrates. They are absolutely not similar to the parents – they have cross-striped body and short back fin. They are very quickly growing predators. They need a plenty of food and devouring of their own smaller congeners is in the order of things for them. At one-year-old age, after reaching of length of 0.5 meter young fishes move to open ocean where join schools of adult individuals. In this case they at once starts to develop as females. Sometimes schools of approximately one-age individuals are formed. In this case the gender depends on place of individual in hierarchy.

This fish species was discovered by Andrey, the forum member.

Psamaphe (Psamaphe gigantea)
Order: Percoid fishes (Perciformes)
Family: Sea swallows (Monodactylidae)
Habitat: Tanganyika passage, coastal zone.
Formation of Tanganyika passage which had separated East Africa (Zinj Land) from other continental platform, began, in effect, from formation in break of Earth crust of whole circuit of Great African lakes: Tanganyika, Nyassa (Malawi), Victoria, and some more several smaller lakes. In due course they had merged to one deep long lake, and then edge of rift had revealed in the south, and ocean waters had rushed to freshwater reservoir. Then narrow gulf had turned to passage, having revealed to all length and completely having separated East Africa from other continent.
When it had taken place, numerous unique species of freshwater fishes evolved in lakes, either have died out, or have receded in rivers, but the formed basin started to be occupied by sea fishes from the south and the north. Among former freshwater inhabitants of these places, however, some species, which also had mastered salt water of passage, were to found. But all the same the significant part of species inhabiting passage, belongs to sea fish families. Psamaphe, the representative of sea swallows family, is one of them.
Psamaphe named after nymph from antique mythology is large predatory fish: length of its body from muzzle tip up to tail tip is about 1 meter. As at all representatives of family to which it belongs, the body of psamaphe is very much extended in height: at meter length the height of fish is up to one and half meters and more. Back and anal fins are peaked, tail is crescent. Pectoral fins are long, pointed, slightly bent, and abdominal fins are reduced up to small spikes (it is characteristic attribute of family). The constitution of fish indicates the fish as excellent swimmer.
At this fish there are large eyes and mouth able to streth in tube for capture of catch. Psamaphe eats small fishes and large plankton crustaceans, catches shrimps and others large, swimming in thickness of water, crustaceans.
The body of psamaphe is colored silvery-blue with dark irregular-shaped spots on back and sides. At the edge of unpaired fins there are wide yellow strips, at males having appreciable orange shade. Males are larger than females, at them there are more abrupt forehead and long fins.
In sea psamaphe prefers top layers of water up to depth 15 - 20 meters. These fishes dive deeper only at the beginning of storm. Psamaphes keep in large schools – up to 20 - 40 fishes of equal age and size. Such way of life helps them in hunting: predators overtake school of crustaceans or small fishes, push them aside from shelters at the bottom, surround and orderly start to catch prey one by one. Sometimes psamaphes approach to the coast and even come in mangrove thickets: these fishes are not avoid of lowered salinity of water, and near coast it is possible to catch many various edible live creatures. For getting animals dug in sand psamaphe has original hunting reception - fish “stands on head” above bottom and by sharp movements of fins creates a wave, which sweep sand in sides. Thus small inhabitants of silt try to rescue by flight, finding out themselves to the predator.
Psamaphes breed in schools in mangrove thickets. Males become appreciably brighter and more contrast than females; strip on their unpaired fins becomes red-orange. By group of two - three ones males surround female ready to spawning and “leap” her away from school to roots of mangrove trees. After short chasing they nestle to the female, and she jets out portion of eggs which are fertilized by males immediately. Then spawned female has a rest, and males chase the next female. Fertility of one female can reach 50 thousand of small grains of roe. The spawning proceeds some days then school swims out to the sea. 2 days later larvae hatch from eggs. They passively hover some hours in thickness of water, and then start to swim and eat actively. After one week larvae turn to fry similar to adult fish by outlines. Fry quickly grow, at bi-monthly age reaching length 2-3 cm, and at one-year-old age about 15 cm. The first year of life young growth spends in mangrove thickets, then schools leave in high sea. Active growth proceeds within the first 5 years of life, at this time fish reaches length 60-70 cm and begins able to breed.

Silver dorida (Dorida splendens)
Order: Percoid fishes (Perciformes)
Family: Sea swallows (Monodactylidae)
Habitat: Indian Ocean, tropical and subtropical waters, pelagic zone.
At the boundary of Holocene and Neocene, oceanic ecosystems were largely destroyed due to the “plankton catastrophe” – a sharp drop in the number of plankton associated with increased volcanic activity and subsequent changes in the chemical composition of ocean waters. This event particularly affected the pelagic zone, where there was a mass extinction of species associated with plankton in terms of nutrition or the spending of the initial stages of the life cycle in it. As a result, in the early Neocene, the process of repopulation of the oceanic pelagic zone by natives of coastal ecosystems began. In the tropical part of the Indian Ocean, monodactylid fishes have become characteristic representatives of the pelagic ichthyofauna.
One of the largest representatives of Monodactylidae is the silver dorida, which lives in the Indian Ocean. The body length of an adult of this species is about 80 cm. Dorida has retained the trunk shape typical for representatives of the family: rounded and slightly elongated in the vertical direction, with very deep dorsal and anal fins, giving the body the crescent shape. The unpaired fins are pointed, translucent and grayish in color. The anus and the bases of the pelvic fins are shifted upwards, almost to the throat of the fish. Pelvic fins are reduced and are made of a single short ray. A hard skin keel stretches along the lower part of the body from the anus to the base of the anal fin. Tail fin is wide, stiff and crescent-shaped. Tail stalk is strong; two longitudinal keels stretch along its sides, under which lie strong muscles that drive the tail in motion. The general color of the body is silvery, bluish-gray on the back.
This species has very large eyes; the iris is silver-gray in color with a reddish tinge in males – this is the only feature of sexual dimorphism. The eyesight of this fish species is good, and for their normal well-being, eye contact with their relatives is important. The mouth is very small and toothless, located on the midline of the eye. The edges of the lips are slightly keratinized.
This species is a schooling pelagic fish; it gathers in shoals numbering up to several dozen fishes. Silver dorida inhabits ocean waters from the surface to a depth of about 100 meters. Usually this fish keeps in the upper layers of the water, searching for prey with the help of sight and smell, and goes to the depths only with the approach of a storm, following its prey. This species feeds exclusively on pelagic soft-bodied invertebrates and fish fry. Doridas often attack large jellyfish and siphonophorae, and eat their tentacles without fear of stinging cells.
Despite living in the open ocean, this species is associated with coastal waters at one stage of its life cycle: dorida spawns in coastal slightly freshened water, opposite the mouths of rivers. Spawning is in schools; at this time separate schools of fishes gather in shoals numbering many thousands of individuals and enter the streams of water of lower salinity. A change in the salinity of the water serves as a signal for the start of spawning. At this time, the males’ eyes turn very red, and they begin to chase groups of females. Pheromones secreted by fishes synchronize the ripening of reproductive products. Inside the shoals, separate schools of fishes that have synchronized their biorhythms are formed, and the eggs are spawned simultaneously by all females from such group. Eggs are pelagic and develop in the upper layers of slightly freshened water. Juveniles stay near the mouths of rivers and occasionally enter mangroves, but as they grow, they leave the coastal zone and move to the open sea. At the age of one year, the length of the fish is about 10 cm; then at the age of 5, with a length of about 40 cm, it becomes capable of reproduction. Life expectancy is over 50 years.

Sparkling cleaner chromis (Neonochromis medicus)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: Tanganyika passage, river mouths with thickets of water plants.
Before split of Africa the territory becoming coast of Tanganyika passage, was the huge valley serving as a receptacle to chain of Great African Lakes. These lakes were richly inhabited by huge amount of various species of fishes among which representatives of cichlids family prevailed. After split of continent and filling of Great Rift Valley with sea water the part of cichlids species has survived, having receded from lakes to rivers. But later some cichlids had adapted to life in sea water of Tanganyika passage.
One of sea species of cichlids is sparkling cleaner chromis. It is a small fish (length of body is about 12 – 15 cm), living alone or in pairs in river estuaries where water is only slightly brackish, and still there are aquatic flowering plants. By constitution it is similar to the majority of lake cichlids dwelt in Holocene in thickets of plants: body is rather deep; head is large (about of 1/5 of all fish length), with big eyes. Prickly part of back fin at males is very high (about 2/3 of body height), on it there are some bright red irregular-shaped spots. It serves as warning signal for other males that the territory is occupied – pair of fishes is territorial; they aggressively banish neighbours, trying to lodge nearby. At the female such ornament is not present. Other unpaired fins are translucent with bluish shine.
Feature of the cleaner chromis is its diet consisting mostly from parasitic worms and crustaceans which are gathering by fishes from skin of other fish species. This species lives in thickets of plants; pair of fishes occupies a large appreciable bush near which they spend “reception” of clients – large fishes, cleaning them from parasites. For “advertising of services” at chromises the attribute making them very appreciable from afar is developed: bright blue “neon” strip on cyaneous body. When fishes swim near the bush of plants serving for them as shelter, shine of their sides involves “client” fishes. From the central part of passage large schools of fishes frequently swim to river mouths for the sanitation – freshened water has pernicious influence to parasites. And cleaner chromises help fishes to have quick and warranted sanitation.
The mouth of This fish species is transformed into scraping grater: strongly turned out lips are covered with set of tiny corneous denticles permitting to scrape off particles of dying off tissue on fins and wounds, to clear gills of worms have stuck to them, to hook and pull out parasitic crustacean has taken root under skin.
Fishes have come to clearing, patiently tolerate all actions of cleaners though sometimes pull because of pain if the cleaner chromis carelessly clears graze of rags of died out skin. Sometimes “client” fishes conceive fights, pushing each other away from the fish - cleaner.
Pair of fishes spawns twice per one year on the chosen plant – large eggs (up to 200 ones) are spawned on leaves. Before spawning male actively cleans leaves, from time to time “inviting” the female to itself. He is colored bright, “crown” on fin becomes almost entirely red. The spawning usually begins in the evening though ceremonies previous to it can take place in the afternoon. Male actively shows to the female cleared leaves, drives off from them fishes and shrimps (sometimes simply making false lunges against nonexistent enemies). In the evening pair of fishes starts to spawn eggs: the female swims along the leaf, laying grains of roe in “line”, and the male swims almost side by side with her, fertilizing spawned eggs. Both parents carefully protect clutch, driving away probable enemies. At this time bright colouring of cleaners grows dull: blue “neon” strip completely disappears, being replaced by line of vertical strokes. During caring of posterity these fishes try to not draw attention of yesterday's “clients”: at approaching of large fishes parents hide in thickets. The posterity hatches after 3 days, and parents at once bring them to the small hole dug out under roots of chosen plant, that current will not carry fry away.
After one week fry starts to swim actively. Colouring of young fishes while resembles parental by nothing: they are black with longitudinal line of white points. Such colouring will be kept at them up to monthly age when they’ll leave parents. At a young fish passed to independent life, to three-monthly age white points start to increase and to merge to one longitude strip. Their colouring changes also: an appreciable blue shine is seemed. Half-year-old fish already can breed. At this age its colouring is already similar to colouring of adult fish, but at males “crown” on back fin will appear only at the end of first year of life.

Figaro, or comb-toothed cleaner (Ctenognathochromis figaro)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: Tanganyika passage, coastal waters.
As against the previous species of fishes, this fish is not the homebody, but the wanderer of coastal waters. It does not have constant territory; it swims among stones and thickets of vegetation, searching for food in different places. Similarly to the sparkling cleaner chromis, this fish relieves other water animals of parasites though the significant part of diet at this fish is made by tiny sedentary sea animals. This species prefers to clean turtles and large pelagic fishes keeping in places where the sparkling cleaner chromis does not live – far from sites of sea with freshened water.
Figaro is very similar externally to the cleaner chromis though at the closer examination distinctions are clearly visible. This fish neither at males, nor at females does not have “crown” of lengthened fin rays. Distinctions in structure of mouth are well appreciable: at this species lips are narrow and smooth, but the bottom jaw is flat and saw-edged in front: it is a main instrument of getting of forage (name Ctenognathochromis means “chromis with comb-looking jaw”). Colouring of fish is very similar to coloring of sparkling cleaner chromis: it is a result of phenomenon, known to people as Muller’s mimicry. Thus natural selection favors to formation and preservation at various species of features of external similarity while both species are equally protected from attack of predators. For cleaner fishes of Tanganyika passage this protection is their role of cleaner in ecosystems. Predatory fishes do not touch all fishes of similar coloring, having shining blue strips on sides.
In details of colouring figaro nevertheless has differences from colouring of sparkling cleaner chromis: the body of this fish is not bright blue, but grey, and neon strip is much wider and longer. It reaches tail fin, and on branchial cover is supplemented with round shining spot.
Fishes of this species do not form constant pairs, meeting only for fulfillment of courtship ritual. For this purpose male builds special “dance pavilion”: he cuts out all seaweed on any flat stone, then literally “polishes” by jaw its surface. After that male starts to invite females, performing in thickness of water above the cleared platform the special dance, swimming along eight-shaped trajectory. He supplements these movements by advertisement sounds – loud clicks. Usually some females living in the neighborhood respond to this signal. They swim together to “dance pavilion” of male, then the male starts to perform the following “figure”: semi-laying on one side, he whirls on the surface of stone, flashing by blue strip. Female ready to spawning joins him, and pair of fishes makes some circles together. Further the generated pair expels all superfluous females and starts spawning. Eggs (up to 100 ones) are spawned on stone. Male fertilizes them, and then female takes all clutch in mouth. Male any more does not takes part in care of posterity. He banishes female, has a rest for some days, clearing “dance pavilion”, and then spawns with the next female.
Female incubating eggs hides anywhere at its territory in cavity between stones. During egg incubating she does not eat. Eggs develop in mouth of the female about 10 days. Hatched larvae even one week stay in mouth of the female, and then start to swim and feed under her supervision. In two weeks they swim out from mother and live independently. The original feature protecting them from predators is early shown blue neon strip on body. Due to this even the youngest fish feels like in safety even near to large predators. Young fishes at once start to work as cleaners, rendering the services at first to small fishes, and then, in process of growth, to larger ones. Sexual maturity appears approximately at one-year-old age.

Small-maled disproporcichla (Disproporcichla micrandra)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: forest rivers of Zinj Land.
The species variability of fishes of cichlid family had reduced to Neocene. It was the result of splitting of Africa to continental mainland and Zinj Land. The line of break in Holocene epoch was marked by chain of Great African Lakes differed in variety of cichlid fauna. When waters of Indian Ocean had filled in Great Rift Valley, many species of cichlids had died out. Some species of these fishes managed to recede to rivers – they became ancestors of various Neocene cichlids.
Representatives of cichlid family are distinguished among bony fishes by various forms of family relations and complex behaviour providing isolation between the species living in the same reservoirs. In Holocene epoch it was possible to distinguish precisely some species of cichlids by features of behaviour at rather similar features of their anatomy. In Neocene at cichlids various tendencies in development of relations between genders were kept. Besides the forms of relations existed in Holocene between fishes of different genders, completely new, earlier not existed ones had appeared.
In short and rapid rivers of Zinj Land one interesting cichlid of Neocene lives, at which mutual relation between genders have got completely fantastical character. This fish is named small-maled disproporcichla, and its specific features completely justify the name.
The female of this species is rather large – it reaches the length of 45 – 50 cm and more. The female differs in rather large head with wide mouth and thick lips. Out of spawning period the female has rather soft colouring – gray-brown with darker back, pale vertical strips and black “mask”. Lips of the female out of spawning period are light grey, and on fins grey points and irregular-shaped spots are scattered. During the spawning its colouring turns brighter and more contrast: the body gets the shade of red clay, vertical strips become black, and lips turn snow-white. The female of disproporcichla is a predator eating small fish and shrimps.
The male of this fish sharply differs from the female. At first sight it is possible to mistake it as the representative of completely other species, and even genus of fishes. Length of the male is only about 10 cm including fins. It has dark blue body with cyan metal shine; on anal fin of male large “egg spots” of orange color are scattered. During the spawning he stretches anal fin and swims right before head of the female, displaying to her these spots. Head of the male is short and high with small mouth. On its forehead the large fat outgrowth is located – it is an attribute of maturity and good physical condition. Eyes of the male have clear silvery shine, and they are surrounded with dark spot, remotely similar to black “mask” of the female. Male eats small water animals.
The ratio between genders at disproporcichla depends on temperature and acidity of water. In soft and acidic water (for example, in rainforest rivers) the ratio of genders at growing up posterity makes approximately three males to one female. In fresh water of neutral acidity the ratio of genders makes approximately 1:1. Therefore more often in population young males prevail a little. While they had not found the female, at them the chance to perish from predators is great. The female means protection and safety for them. Therefore the male gets attached not as much to territory, as much to the female living at this area. He continuously follows the female and behaves very aggressively, driving possible contenders away from the female.
Disproporcichla lives in wood rivers overgrown with water vegetation along riverbanks. Among plants fishes find shelter and rear posterity. The spawning of disproporcichla passes originally. Stimulus for a spawning is the rise of temperature of water up to +30°С. During courtship displays male stimulates the female to egg spawning, showing to her “egg spots” on anal fin. For this purpose he literally nestles by side against the head of the female, and stretches fins, overlapping by them a field of vision of the female. Also he pinches the female by lips for bases of pectoral fins and pushes her to side by all body. At the culmination moment of courtship displays male moves to the tail of the female and swims along all her body, having nestled to her by side. Under action of such stimulation the female spawns a portion of large eggs. In clutch of disproporcichla it may be up to 200 – 250 eggs spawned at once.
Having spawned eggs, the female at once takes them away to throat pouch for incubating. And this moment the male actively includes to the process of spawning. He squeezes in mouth of the female (female lips turning white during the spawning serve as the stimulus for this purpose), and fertilizes eggs right in her mouth. After that the male cautiously leaves the mouth of the female, and keeps permanently near to her. From time to time male gets in mouth of the female and searches for sterile eggs. He takes eggs in mouth and clears them of parasites and dirt.
Term of incubating makes about three weeks. This entire time female eats of nothing. Male protects her from other males - at disproporcichla female aggression relatively to males of the species is reduced, therefore stranger male can easily “enter trust” and destroy another's eggs. When from eggs young fishes hatch, they keep for some time in mouth of the female, and the male regularly examines them. Approximately at one week age they start to swim, and cares increase at the male. It “pastures” posterity and protects hatch from small predators, such as water bugs, larvae of dragonflies and beetles, if necessary. At danger it quickly returns posterity to the mouth of the female.
First days of life young fishes have no gender – at these fishes the gender is not determined genetically. Further depending on conditions of environment and degree of development they turn to males and females. Males in development quickly stop in growth, but get bright colouring rather early. Because of it the part of them perishes from predators, but the male founded the female, provides safety till entire further life to itself. Life expectancy of females of these fishes makes over 30 years. The male lives less, rather than female – till 15 years.

Cuckoo chromis (Cuculichromis parasiticus)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: forest rivers of Zinj Land.
In early Neocene, when the great split of African continent took place, numerous species and subspecies of cichlids evolved for millions of years of isolation in Great African Lakes, had got a serious problem. Earlier people caught representatives of these species, then had introduced in some lakes predatory fishes preyed lake endemics and had undermined their forage reserve. But geological forces had put much more serious problem to fishes. Lakes had turned first to narrow gulf of Indian Ocean, and then turned to Tanganyica Passage. This event had completely separated Eastern Africa (Zinj Land) from the basic continent. In these conditions the majority of endemic fishes had died out, but some species of fishes had managed to adapt to life in rivers flowed earlier into lakes, and then into Tanganyica passage. Cichlids also were among them.
Due to high adaptive potential cichlids had developed a plenty of biotopes in reservoirs of Zinj Land. Among them even extremely strictly specialized species had appeared.
The amazing cichlid Disproporcichla lives in rivers of Zinj Land – at this fish male is many times smaller, than female. The female of disproporcichla is a predator representing danger to small fishes and shrimps. It reliably protects the posterity, and the male, tiny creature of dark blue colouring, uses her protection. At the aggression and predatory behaviour the female of disproporcichla has one “weak point”, which is caused by her instincts. She does not touch the male of own species and consequently does not attack fishes having more or less similarity to him. The species of small cichlids, cuckoo chromis, the descendant of certain species of chromises of Tanganyica Lake missed in Neocene, dexterously uses it, skilfully imitating the male of disproporcichla.
It is fish only 5 – 6 centimeters long. The male is a little bit larger, than the female, and it has rather large head. Out of spawning season both genders of this fish have the colouring strongly distinguished from colouring of the male of disproporcichla – fishes have the bright orange colouring with small black spots forming “marble” pattern, black back, vertical dark brown strip stretching across the eye; dark iris of eye. Having such colouring they diligently avoid meetings with the female of disproporcichla which may swallow them easily. But the male of this fish does not pay attention to them at all, because it does not see competitors in them. But in spawning season both fishes change colouring and body shape. At fishes of both genders fat “helmet” on head grows, and colouring turns to dark blue with slight metal shine. They differ from the male of disproporcichla in lighter forehead and dark eyes (at the male of disproporcichla eyes shine silver). On anal fin these fishes also have “egg spots”, but they are black. Having such colouring cuckoo chromis rather successfully imitates the male of disproporcichla. And in courtship season the relation of disproporcichla to these fishes varies to opposite one. The disproporcichla female has boundless confidence to dexterous imitators, but the male begins to see contenders in them, and furiously attacks them.
The purpose of this “masquerade” is simple, but its achievement is much more difficult. The task of cuckoo chromises is to place stealthily eggs during the spawning right in mouth to disproporcichla incubating own clutch. They use similarity to the male of this species to penetrate into the mouth of female and to lay eggs in clutch, having had eaten a part of disproporcichla’s eggs. The spawning of these fishes begins almost simultaneously with spawning of disproporcichlas. The pair of fishes simply waits, while the disproporcichla female will take eggs in mouth for incubating. Then the female of cuckoo chromis under the guise of the male of disproporcichla penetrates into her mouth, eats a part of eggs and lays her own eggs. At this time the male distracts the disproporcichla male, showing bright colouring at some distance from spawning fishes. After that action partners exchange roles, and male of cuckoo chromis fertilizes eggs right mouth of disproporcichla female, while the female withdraws aside disproporcichla male. Having finished the spawning, pair of these fishes departures and quickly changes colouring, giving disproporcichlas an opportunity to care of their posterity.
Fry of cuckoo chromis hatch earlier, than posterity of disproporcichla. But they do not attack fry of host species. They stay in mouth of disproporcichla until the hatched posterity of disproporcichla will start to swim. First days fry of both species keep in one common school, in common using protection of female and care of male of disproporcichla. Approximately in two weeks the posterity of cuckoo chromis leaves foster parents and passes to independent life. Young fishes become adult at the age of two years.
Cuckoo chromises live in pairs. They prefer to live at the edge of territory of breeding pair of disproporcichlas and not to catch eyes of the male of this fish just before the spawning time. They are very cautious, and at first signs of danger hide in underwater vegetation. These fishes eat small aquatic animals – larvae of insects, leeches and other worms.

Sharp-toothed cichlopike (Esocichla rapax)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: Zinj Land, rivers of the western part of subcontinent.
In Holocene fishes of cichlid family dominated or made a significant part of specific structure of ichthyofauna in some reservoirs of the Earth. In Neocene due to global ecological crisis the role of these fishes in ecosystems has exchanged. The destiny of cichlids in New World is to be rather small peaceful fishes. In this part of the world characid fishes, reaching the monstrous size, dominate in reservoirs. Split of Africa had caused disappearance of the majority of species of endemic cichlids inhabited Great African Lakes when these lakes became a part of Tanganyica Passage. Isolation at Zinj Land had resulted in active adaptive radiation of cichlids among which ecological analogues of fishes of other groups had appeared. One species of cichlids, living in Zinj Land, had occupied an ecological niche of large freshwater predatory fish. Arrow-like body and large head with long jaws have made this fish similar to pike, that has determined its name – the cichlopike. In Holocene epoch pike-like cichlids of genus Crenicichla lived in South America. But external similarity of cichlopike from Zinj Land and pikes of Eurasia and North America is even more.
Cichlopike constantly lives in fresh water. Using marshy sites of forest it had settled along whole western coast of Zinj Land, in rivers running into Tanganyica Passage. She is rather large fish reaching one meter length. At it the sexual dimorphism is expressed: male is larger and more slender, rather than the female, and it also is colored much brighter.
Body of cichlopike is arrow-shaped, with short tail and wide tail fin. Forward part of body is strongly extended and flat; head is also flattened a little. Mouth of cichlopike is wide and extending to short tube. Due to such structure of mouth fish eats small catch, which has appeared nearby – it is enough to it to open the mouth and the prey is engulfed in it by strong stream of water. Eyes of cichlopike are big: fish hunts in day time, and mainly with the help of sight.
The prickly part of back fin is presented only by short spikes connected by rudimentary membrane. A line of these spikes stretches approximately from the nape to the beginning of soft part of back fin. The soft part of back fin and anal fin are shifted back and pulled together to tail. Such structure is typical for fish overtaking catch by fast throw from an ambush. Back of cichlopike is dark grey; sides are silvery with greenish shade and plenty of dark vertical strips. For giving of signals to neighbours this fish has bright recognition marks on anal fin and the bottom part of tail fin, especially appreciable at males. Anal fin of male is red with several white spots; at female it is red-brown without spots.
Cichlopike avoids muddy water and reservoirs strongly overgrown with underwater vegetation. It lives in clean water with slow current, and usually slowly swims near water surface. Favourite place of an ambush at cichlopike is roots of floating plants which small thickets drift with the current. Cichlopike is not specialized relatively to food, and eats practically any creature which it can swallow. It hunts frogs, pelagic fishes and shrimps, and also catches small ground vertebrates appeared in water – birds, reptiles and mammals. Each fish occupies the certain site in the river, but hides in its various parts where at present there are floating plants. Adult fishes regularly declare the rights to territory, jumping out from water and plopping down with loud splash. Such feature of behaviour causes in fishes living in the neighbourhood, something like “chain reaction”: when one fish plops down in water, individuals living in the neighbourhood with it, also jump out from water, as if reminding about their own presence.
At cichlopike constant pairs are not forming. This fish spawns on sandy bottom, choosing the shallow sites of river closed from looks of aerial and ground predators by floating plants. The male occupies the certain territory, and settles it: it pulls out all plants preventing him, digs by mouth small hole in sand and invites to it females swimming near. At this time his body darkens and turns graphite-grey, and eyes get silvery shine. Anal and tail fins, and also back part of back fin become cherry-red. Involving the female to the nest made by him, male swims around the hole, and emerges to water surface, displaying itself. Fishes spawn in hole, and male at once takes away fertilized eggs in mouth for incubating.
In clutch of cichlopike it may be up to 100 rather large eggs. The posterity hatches approximately in 10 days, and keeps in mouth of the male till about one week while the yolk sac resolves. All this time the male eats of nothing, and hides from large predators among underwater vegetation or at the bottom.
Fry able to swim keep near the male, and it protects posterity till about ten days. During this period in case of danger fry hide in mouth of the male. Rearing posterity, male keeps in thickets of floating plants where it is easier to young growth to find food. Young fishes eat larvae of insects and shrimps. They grow quickly – to the age of half-year young fish reaches length of 10 cm, and for the next year grows up to 30 cm. Till the first year of life young fishes live in thickets of underwater plants, but later pass to life at the water surface. At one-year-old cichlopike body shape typical for these fishes starts to express – jaws and forward part of body extend quickly, and back fin and tail slow down in growth. At the age of 5 years, at length about 60 centimeters cichlopikes become sexual matured. They reach the size typical for this species at the age of about 10 years. Life expectancy of cichlopike reaches 35-40 years.

Dimorphochromis ngege (Dimorphochromis ngege)
Order: Percoid fishes (Perciformes), suborder Labroidei
Family: Cichlids (Cichlidae)
Habitat: Zinj Land, rivers in the eastern part of the microcontinent.
In the human era, some fishes of the cichlid family gained advantages in the struggle for existence, while others suffered significant damage. A significant number of small, local and endemic species have died out, but at the same time, due to human activity, some species have spread widely over the Earth and over millions of years of life in new places have turned into new species. Due to the transformation of the Great African Lakes into the Tanganyika Strait, numerous species of lake cichlids have become extinct, but some widespread species have survived, and their descendants inhabit both continental Africa and Zinj Land in abundance.
One of the endemic species of Zinj Land is dimorphochromis ngege, a descendant of the widespread Nile tilapia (Oreochromis niloticus); “ngege” is one of the local names of this ancestral species. This species has developed a very pronounced sexual dimorphism in the process of evolution. A similar phenomenon is displayed by a species living in the neighborhood – disproporcichla (Disproporcichla micrandra), but in dimorphochromis, the manifestation of dimorphism is more typical: in this species, a large male protects a harem of several small females.
The male of this species is about twice as large as the female, reaching a length of about 40 cm. It has a powerful body of moderate length with wide fins and a forked tail. Body has a bluish-green color with a metallic sheen and several dark vertical stripes on the sides; chest and belly are light green. Fins are transparent, greenish in color, with darker bases. Head is sharply different in color from the rest of the body: it is yellowish-white; a massive fatty growth of white color rises on the forehead. The eyes of the fish are circled with black rings; in the upper posterior quarter of the ring on a black background there is a shining white or bluish smear, mimicking the reflection of light on the cornea of the eye. The iris of the eye is of dark cherry color. Males of this species have thick lips covered with a gray-white cross-striped pattern, giving the impression of large teeth. Displaying himself, the male spreads in sides the gill covers and straightens the folds of the skin, enhancing the impression of his display.
Dimorphochromis female differs greatly in appearance from the male, significantly inferior to him in length. Its color is bright green with vertical “marble” stripes of brown color; lips are white and relatively thin. The iris of the eye is bright red.
This species feeds mainly on plants and small aquatic invertebrates. Males can attack small fish. The species keeps in harems, numbering up to a dozen adult females with one male. Usually fishes keep in the vicinity of natural shelters – near drowned trees or rocks. Despite the inclination to feeding on plants, fishes leave several bushes near their territory as a shelter. They also dig tunnels under driftwood. Arranging a shelter, the male can drag driftwood pieces up to one meter long under water. The male patrols the surroundings of his possessions, driving away rivals, competitors from other species, and even small crocodile monitor lizards and turtles. The usual protective technique of the male is to rush at the trespasser from the shelter, spreading the gill covers. Due to the surprise factor, many of the violators leave its territory. If it happens not quickly enough, the male strikes a ramming blow with his head.
Reproduction occurs up to 3 times a year. Females incubate eggs in their mouths, having preserved the behavioral features characteristic of their ancestors. This species has group spawning: the females spawn their eggs to the bottom at the same time, and the male fertilizes all the eggs at once, swimming among the females. When taking eggs for incubation, females often pick up other ones’ eggs in their mouths, but they grow others’ offspring on a par with their own. This species has no problems with single males, since sex is determined behaviorally: the male is the dominant individual in the pack and guards the harem of females. If the male dies, the main female takes his place and in a month is transformed into a full-grade male, after which it begins to grow rapidly. Only males who have lost their harem can afford to attack the opponent's harem and lead away females ready for reproduction from it.
There are up to 50 large eggs in the clutch. Incubation lasts up to 5 days, but young fishes hide in the mother’s mouth for up to 2 weeks. The male does not take direct care of the offspring. Young fishes in the process of growth get the appearance of a female, and only when the hierarchy in their school is established, a male individual is singled out among them. Sexual maturity comes at the age of 6-7 months; life expectancy is up to 10 years.

Nurse mayaichthys (Mayaichthys patronus)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: South America, shallow rivers of tropical zone.
After global climatic changes at the border of Holocene and Neocene among fish population of rivers of South America there were significant changes. The majority of heat-loving fish species had died out, and the variety of some groups of fishes was essentially reduced. After the restoration of conditions acceptable to life of heat-loving fauna at different groups of fishes the chance to grasp domination in Amason basin had appeared; and characid fishes have taken advantage more successfully than others. In Neocene characids became most awful predators of South-American rivers, and another earlier multifarious group, cichlids, has appreciably yield positions: among them there are few large species, and their variety was essentially reduced in comparison with Holocene epoch. But they survive among various characids due to occurrence and perfection of effective ways of posterity care. At these fishes much more fry survive, rather than at more fruitful characids spreading eggs to the mercy of fate or not caring about fry.
Among Neocenic cichlids it is a lot of species, developing during evolution original receptions of care of posterity. Among them the mayaichthys, the descendant of one cichlasoma species (Cichlasoma), bearing eggs on the body, is especially remarkable.
Mayaichthys is medium-sized fish: about 25 cm long. The body of this species is deep and short, strongly compressed from sides, rounded, and covered with small scales. This fish is colored rather brightly: forward part of body is golden-yellow (at males - copper-red), back one is green. On body wide black faltering longitudinal strip passes. During spawning head of male becomes brighter, getting violet shade, and strip on body, on the contrary, fades. Head of mayaichthys is rather large, at males on forehead the big fat cushion grows. In season of spawning this cushion increases and sticks forward, as ram.
Mayaichthys is rather sluggish fish: its favorite habitat includes thickets of aquatic plants in well warmed up shallow rivers. This fish swims rather slowly: at it there are wide rounded fins and rounded tail.
Mouth of mayaichthys is rather small: the basic food of this fish is larvae of midges and mosquitoes, and also other water insects. Sometimes mayaichthyses eat small snails, leeches and other worms.
As well as all cichlids, to mayaichthyses the care of posterity, shown very originally, is peculiar. During spawning on body of fishes the special nutritious slime is secreting. To people such feature at discuses (Simphysodon), angelfishes (Pterophyllum) and some other cichlids was known. But all these cichlids spawned eggs on any substratum, and only fed with it hatched fry. The care of posterity at mayaichthyses had turned further. The female spawns eggs on stone or cleared leaves of plant. But after it the male carries by mouth eggs spawned by female on her sides, pastes to slime and fertilizes. The incubating of eggs proceeds within one week. All this time the female hides in thickets, trying to not give out its presence, and does not eat at all. Male in this period protects environmental territory, driving away not only small fishes, but also the fishes surpassing him in size. Showing the aggression, he opens mouth and spreads branchial covers in sides. At such moment brilliant blue spots latent under skin plicas become well appreciable. If the newcomer does not leave, male supports the threat with ram impact of forehead with thick fat cushion.
Embryos develop in the beginning due to stocks of yolk. The yolk sac of the embryo quickly becomes empty, but completely does not disappear. Yet not hatched larva nestles by it against skin of the mother, and starts to eat her slime. For this purpose on surface of yolk sac fibers which, as if roots, penetrate into slime produced by skin of the female, develop. Through blood vessels nutrients absorb in blood of larva, and it grows intensively. Due to fibers eggs keep on sides of female rather strongly, not dropping down even at sharp jerks of adult fish. When fry is ready to hatch and start to shake from themselves rests of egg shell, male accurately helps them, cautiously removing it. Also he in due time examines the female, removing from her sides became white not fertilized grains of roe.
Long development and additional feed have favorably an effect for larvae of mayaichthyses: after hatching they are able to swim and eat actively almost at once, having passed critical for other fishes stage of helpless inactive larva. When fry of mayaichthyses start to swim, they eat also slime of male which takes an active part in cultivation of larvae. The fish, ready to feed posterity, darkens and rises side by side with fish on which young growth sits. It serves as a signal for fry, and they pass to other parent.
Young mayaichthyses do not depend on presence in right moment of any special species of live forage, and the interest of their survival rate is very high: about 80 % of larvae lives up to independence. At the age of two weeks they cease to feed with slime of parents, gradually passing to feeding by small water animals. At this age young small fishes are translucent, colored yellowish with black longitudinal strip. Female drives flight of fry in thickets, and male keeps behind, adjusting fry lagging behind and swimming in sides. But gradually it is more and more difficult to them to keep flight of fry together and sooner or later young fishes one by one abandon parents. At the age of 16 - 18 months young fishes become adults. At them colouring, characteristic for this species is gradually shown, but males will get magnificent fat “crowns” only at two-year-old age. Then at them the reddish shade in colouring will appear.

Nurse aspredocichla (Aspredocichla pseudoaspredo)
Order: Percoid fishes (Perciformes)
Family: Cichlids (Cichlidae)
Habitat: South America, rivers of tropical zone.
During evolution various species of fishes of Cichlidae family have developed surprising ways of care of posterity. Among them there are species protecting and fanning them by fins eggs laid on leaves of plants and stones. Some species brood eggs in mouth, keeping strict fast. There are child-loving parents feeding fry with nutritious slime secreting on body, and there are also ones simply “fosteraging” eggs to related species of fishes. But in Neocene among cichlids the nurse aspredocichla has appeared, which, perhaps, has surpassed in child-loving all its relatives.
This fish uses the same way of care of posterity which South-American catfish Aspredo and its neighbour, the frog of Pipa genus have developed independently from each other. At these species of animals eggs develop on skin, and developing embryos are supplied with feed due to parent organism. Blood vessels sprout in skin, and surround grains of roe, supplying them with substances necessary for life.
Externally the aspredocichla has only distant similarity to mayaichthys: at it there are the same short body about 25 - 30 cm long, and wide rounded fins. But constitution of the aspredocichla is more powerful: its body is almost cylindrical; head is large with big mouth. The body of these fishes is colored bluish-green with light yellow stomach. Separate scales on back of the male at movement literally flash by blue sparks. Occasionally same scales are present at females, but in much smaller quantity. The back fin of male is bordered by red strip which becomes even wider and brighter to the moment of spawning.
The body of fishes is covered with large relief scales. However on chest of the female there is an extensive site of scaleless skin. Its role in life of these fishes is really invaluable: it serves for egg incubating.
Aspredocichla lives in wood rivers of South America, preferring to keep among plants. It is a predator eating various small animals – larvae of dragonflies, water beetles, small snails and fry of fishes.
In spawning season colouring of the male is changing: it darkens, and the bottom part of body from throat up to pectoral fins becomes almost white. On background of velvet-black back of the male bright blue flashes seem especially brightly when the male stands in ray of sunlight, falling in water through crones of trees. On his head to time of spawning the big fat cushion similar to helmet grows. The male chooses bush of plant with wide leaves, and clears territory around of it: it drags dust by mouth, breaks off from bush yellowed leaves, tears out stalks of plants in radius about half meter from bush. On bush the male accurately clears some leaves by lips, and then starts courtship demonstrations. The male in courtship dress is remarkable on the background of greenery of bush. Having straightened fins, he swims around of it, from time to time rushing towards to fishes swimming near.
If the met fish is the female ready to spawning, the male starts to entice her to the plant. He swirls around of the chosen female, having straightened fins and from time to time stopping to show itself. Female answers to his courtship, also changing colouring: her back becomes black, and stomach turns white. During courtship games skin on chest and throat of the female becomes pinkish because of dilatation of blood vessels, that it serves as additional stimulus for the male. The female also shows to the male belly full of eggs. The male “leads” her to prepared leaves of plant where spawning takes place.
During spawning eggs are laying on leaves, and male fertilizes them. After all eggs are spawned, the female swims up to the male, having turned to him by side and having bent. Pink color of the bottom part of female body stimulates the following act of reproductive behavior of fishes: male cautiously gathers eggs in a mouth by small portions, and accurately displays them on chest of the female. When one side of the female is covered with eggs, she turns by other side, and the male repeats the actions while all eggs will appear on body of the female. In full clutch at these fishes it happens up to 80 - 100 large grains of roe, and all of them are accurately displayed by the male on throat and chest of the female. At grains of roe there are sticky shells, and they strongly enough keep on her body.
Contact of eggs and skin causes the certain physiological reaction at the fish, as a result of which blood vessels sprout in top layer of skin and close approach to shells of eggs. The skin partly swells, and eggs appear plunged in it at half. Thus not fertilized grains of roe are torn away.
The female with eggs hides in any shelter, and male incurs care of her. He gathers food, cautiously swims up to the female and feeds her, giving food from mouth in mouth.
Development of eggs lasts about one week. At this time the female strongly grows thin, despite of care of the male. The developing posterity exhausts the female, but larvae of this species safely passes critical for many fishes stage of helpless larva.
Fry of aspredocichla is rather large: about 1 cm long. Young growth at once starts to swim and eat actively. First time it is translucent, and on the body there only pigmented specks are appreciable. Later spots merge to a longitudinal strip.
The larvae first some days of life eat slime of parents: in the beginning the care of them is incurred by the male, and the female grows fat, restoring after egg bearing. In case of danger parents hide fry in mouth even then when young small fishes reach length 2 cm.
Young fishes have quite good chances of survival at young age due to care of parents. But rather few from them will live up to maturity - three-year age. The maximal life expectancy of the aspredocichla is about 14-16 years.

Flat-headed cryptocichla (Cryptocichla planicephala)
Order: Percoid fishes (Perciformes), suborder Labroidei
Family: Cichlids (Cichlidae)
Habitat: Great Antigua, rivers.
The formation of the Antillean Land Bridge in the first half of Neocene contributed to the settlement of not only land, but also freshwater fauna. Representatives of the diverse South American ichthyofauna migrated from South America to the north, and this resulted in the appearance of numerous species of freshwater fish in the rivers of the Caribbean islands.
Cichlids successfully settled to the north due to their ability to endure being in seawater, which allowed them to cross narrow sea straits. This allowed them to settle across the islands among the first, along with the descendants of marine fishes. In the process of adaptive radiation, cichlids have evolved to a number of specialized forms in island ecosystems. One of them is a flat-headed cryptocichla that lives in the rivers of the Great Antigua island.
This species is an ambush predator and inhabits shallow forest rivers and streams. The length of an adult fish is up to 15 cm, of which about a third is an elongated head with large mobile eyes and a wide-opening toothy mouth.
The body of this fish is muscular, slender, almost cylindrical, with short fins and a powerful tail stalk. Tail fin is rounded; dorsal fin is short, with strong spines. The body color is dark green with lighter spots on the sides. In various rivers, there are deviations in its coloration – brown, yellowish and gray color forms, as well as individuals of intermediate colorations. Throat, lower jaw and belly are white. The unpaired fins are transparent, with numerous dark spots at the base. The eyes are golden in color.
Flat-headed cryptocichla is a bnthic predator that prefers to ambush prey. Usually the fish slightly buries itself in a layer of rotten leaves or lies among the stems of underwater plants. Due to its camouflage coloring, it is almost invisible to other animals. Its favorite prey includes small crayfish and shrimp, fishes of suitable size and aquatic insects.
This fish species is monogamous. During courtship, males behave cautiously, because an aggressive female can attack a male and cause him serious injuries. Usually, unsuccessful males, after such unsuccessful attempts to form a breeding pair, have injuries of the upper jaw, in which part of the dentition turns out to be broken and turned to the side or forward. The female gradually gets used to the presence of a male on the border of her territory, and during courtship, she no longer rushes at him. The male gets a courtship dress – dark, almost black, with a dazzling white belly and sparkling golden eyes. A pair of fishes, acting together, cleans the lower surface of a wide leaf of a water plant and spawns up to 200 large eggs on it. The male gets back its camouflage coloration and stays to take care of the clutch, while the female patrols the territory, violently attacking fishes even larger than her own size. Incubation lasts about 50 hours. The fry hang on the leaf for the first time; then juveniles begin to swim. Both parents take care of them for about two weeks, protecting them from enemies and feeding them with small invertebrates, caught and slightly masticated. Having grown up to independence, young fishes avoid meetings with adults, since cannibalism is very characteristic feature of this fish species.
Sexual maturity comes at the age of 13-14 months; life expectancy is about 10 years.

Limestone Cave Goby (Speleomogurndoides pallidus)
Order: Percoid fishes (Perciformes)
Family: Sleeper Gobies (Eleotridae)
Habitat: Underground flooded limestone cave systems in the Great Dividing Range of eastern Meganesia.
The native fish fauna of Australia is generally poor due to the nature of the land there, but some native fish have left descendants in Neocene Meganesia.
The Limestone Cave Goby is a descendant of estuarine sleeper gobies which expanded to replace the native freshwater gobies of the genus Mogurnda, which were endangered in the Holocene. Eleotridae have had previous history of colonizing cave waterways, and so it happened in the Neocene.
This fish is relatively small, pale pinkish white and colourless, reaching about 10 centimetres long, body is cigar shaped. Caudal fin is broad and rounded, dorsal and anal fins are low and run the length of the body, pectoral fins are broad. Mouth is sub-terminal and large, and can engulf prey, which consists of cave-dwelling crustaceans and insects, as well as surface insects that are washed into the caves. Eyes are tiny and not visible externally, sitting under the skin. These fish are fairly sedentary when not seeking food or a mate, and will hover in the water or rest on rock surfaces underwater.
These fish are solitary but tolerate others of their own kind. When a female is ready to mate, her bodily mucus takes on a certain smell, and males seek her out. She will lay a clutch of over a thousand eggs, in batches, which she sticks to the upper side of a sheltered rock. These eggs are fertilized by the male, who then takes care of them by guarding them and fanning them to keep them oxygenated. The fry hatch about a week later, and sexual maturity is at 8 months. Lifespan is 4 or 5 years. It is generally the dominant predator in its environment, and has no predators except when young, from cannibalism.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Eyre Frog-Goby (Ranomogurnda rapax)
Order: Percoid fishes (Perciformes)
Family: Sleeper Gobies (Eleotridae)
Habitat: Weedy and muddy bottoms of Eyre Gulf.
Against the onslaught of foreign invasive fish in Holocene Australia, Sleeper Gobies (Eleotridae) are successful in Neocene Meganesia as they are in many places. Specialized forms exist here as they do elsewhere in Eurasia, independently derived.
The Eyre Frog-Goby is a mid sized fish, reaching up to 35 centimetres long, and weighing up to 1.4 kilograms. It has come to resemble toadfish of the northern hemisphere (Batrachoididae), or the stone fish of the southern hemisphere (Scorpaenidae). Its body is short and wide at the front, narrowing quickly to a large rounded caudal fin. Pectoral fins are large and broad, forming a fan shape, strong in order to move slowly along the sea floor, soft dorsal and anal fins are long and broad. Coloration is a dark, mottled greenish brown, with lighter bands and spots on the body and in cross bars along the fins. The head and body are covered in ridges and growths of skin that are mottled and cryptic in shape and colour, allowing it to blend in with sea floor vegetation and debris. Mouth is wide and broad, extending to suck prey in, eyes are large and protrude above the head. Prey is caught in ambush, and includes smaller fish, shrimp, crabs, and the young of larger fish.
It is dictated by the nature of Eyre Gulf, that this fish and any other residents have to withstand poor conditions of salinity and fluctuations in oxygen. Indeed, in this regard, Frog Goby converges upon its archetype, the toadfish, as well as inheriting tough attributes from its ancestor. This fish is generally a solitary homebody by nature, and occupies a small territory that contains enough adequate places in which to hunt for prey.
During the wet season (September to December), males seek out an adequate underwater snag or rock, and make overtures to attract the female. They produce a drumming with their swim-bladders, which attains a percussive sound, becoming rapid. The female and male make a nest among the weeds and snags, and lay a clutch of about 60 large eggs, which are brooded by the male, who cleans them and fans them to keep them well oxygenated, fry hatch after about 13 days. Young stay with their father for a few days until the yolk is absorbed and they learn to swim. Lifespan of this fish is about 15 years maximum.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Brobdignag Bully (Barogobiomorphus gigas)
Order: Percoid fishes (Perciformes)
Family: Sleeper Gobies (Eleotridae)
Habitat: Slow flowing rivers and creeks, upper reaches of estuaries, North and South Islands of New Zealand.
Isolation is a mechanism by which aspects of evolution and speciation are catalysed, and islands do this extremely well. Smaller fish able to tolerate a wide range of salinities, Sleeper Gobies and Galaxias, became unique in the habitats of New Zealand in the Holocene. Some of those forms were very large for their group.
This has happened again in the Neocene of New Zealand, Bullys (genus Gobiomorphus) were a genus of endemic Sleeper Goby in New Zealand's Holocene, their descendants in the Neocene are even more unique.
The Brobdignag Bully is one of the largest sleeper gobies, exceeding the biggest Holocene species. It reaches lengths of up to 1 meter, large older individuals may surpass this. Body-shape is somewhat typical of Eleotridae, but forepart of the body is thicker, and head is longer in proportion to the rest of the body. First and second dorsal fins are moderate size and rounded, pectoral and pelvic fins are moved forward, broad and round. Tail fin is large and round in profile, anal fin is small and runs some length along the underside. Head is large and takes up almost a third of the body-length, mouth is large and protruding with long pointed teeth, jaw is under-slung with large fleshy lips. Scales are externally apparent, coloration is a muddy brown colour, mottled with paler grey on parts of the upper side, fins are opaque and brownish grey. Eyes are large and protruding, eyesight is sensitive to movement.
This fish is a sit-and-wait predator, it will sit on the riverbed, propping itself up with its fore fins, usually among aquatic vegetation or in lee of a snag. Once prey is spotted, it surges forward in a short lunge and seizes the prey in it's jaws. Prey usually consists of smaller fish and aquatic amphibians, but shrimp and young crayfish are also taken.
Breeding occurs when water is high, between May and September, males will choose a secluded spawning site near a crevice or snag. They begin to attract females by fanning and undulating their fins, and making short lunges, a male may seek out a nearby female and push her towards his spawning site. Once the female submits to mate, she will lay up to 100 sticky eggs adhering to a stone or piece of wood, at the chosen site. The male will fertilise them as she lays, and continues to actively defend her until this act is complete. The father actively defends the spawning site and may attack intruders or rival males. Eggs are brooded by the male, fanning them with his fins, after 10 days they begin to hatch and he will leave. Fry are planktonic and feed on small plankton such as crustaceans, sexual maturity is reached within 2 years. Individuals that reach adulthood may live as long as 30 years, predators include larger fish, big aquatic amphibians, when they are smaller they may be consumed by waterbirds and mustelids.

This fish species was discovered by Timothy Morris, Adelaide, Australia.

European river sleeper (Neoperccottus europaeus)
Order: Percoid fishes (Perciformes)
Family: Freshwater sleepers (Odontobutidae)
Habitats: central and eastern Europe to the Ural Mountains, all kinds of permanent reservoirs with stagnant or slow-flowing water.
In the human era, Chinese sleeper (Perccottus glenii), a Far Eastern fish from Odontobutidae family, was introduced to eastern Europe, where it successfully bred and superseded the native ichthyofauna. Due to its unpretentiousness, short life cycle and small size, this fish managed to survive the Holocene-Neocene extinction and preserved viable populations in a significant part of its range. The reservoirs of Neocene Europe are inhabited by one of its descendants – European river sleeper. It is a small fish, no more than 10 cm long, little changed outwardly compared to its ancestor. Fishes of this species have a gray-green color with a stripe of brown spots along the side; males turn coal-black during the breeding season. Skin lacks scales and is covered with slime and permeated with a large number of blood vessels.
European river sleeper is a slow-moving benthic fish preferring to keep in thickets of plants or in other shelters. Its fins are rounded and relatively short; slime causing severe irritation when pricked is secreted on the spines in the first dorsal fin. Head is large (about 1/5 of the overall length of the fish) with a wide mouth and eyes shifted upwards.
These fishes inhabit small stagnant or low-flowing reservoirs with dense vegetation and are completely undemanding to water quality and oxygen levels$ they can endure partial drying of the reservoir. In such conditions, the fish receives a significant amount of oxygen it needs through the skin: the blood vessels expand, giving the skin color a light reddish hue. From its ancestor, this species also inherited the ability to freeze into ice, but it is mainly resorted to by individuals living in the north-eastern part of the range.
European river sleeper is an exclusively zoophagous fish feeding on various aquatic invertebrates, amphibian larvae, eggs and young fish, including its own ones. Thus, the fish provides regulation of the number of its own population. In the north of the species’ range, there are reservoirs with a “monoculture” of this species, where no other species survives.
The life cycle is exceptionally fast: sexual maturity comes at the age of 5-7 months and at the age of 1 year in the northern part of the range; life expectancy is 2-3 years. In the north of the range, five-year-old “old-timers” are occasionally found. Spawning usually takes place in late spring or early summer, when the water in the fish habitats warms up well. In the south of the range, fishes that have hatched in the spring may have time to spawn eggs in the autumn of the same year. Fertility is about five hundred eggs, but the survival rate of the offspring is very high due to parental care. The male builds a spherical nest of plant particles, which he holds together with slime, after which he protects the eggs and larvae for up to two weeks, which provides some protection from cannibalism. At this time, it gets a dark coloration, and attacks aggressively any animals approaching the nest.

This fish species was discovered by Kazimir Adamovich, the forum member.

European blenny sleeper (Pseudoblennius pseudoblennius)
Order: Percoid fishes (Perciformes)
Family: Freshwater sleepers (Odontobutidae)
Habitats: eastern Europe, rivers and streams with sandy bottoms in the basin of the Fourseas; the Balkans.
European blenny sleeper is one of the numerous descendants of the Chinese sleeper (Perccottus glenii), which has found a new homeland in Europe due to human activity. In the absence of natural enemies, having great competitiveness, this species survived successfully the era of ecological crisis at the turn of Holocene and Neocene, and displayed a large-scale adaptive radiation, giving rise to many descendants occupying various ecological niches.
This species looks similar to representatives of blenny family (Blenniidae). The head is shorter and wider than at the ancestor, with large mobile eyes; body is more elongated; pectoral fins have become longer and wider, the anal and second dorsal fins stretch almost to the tail. The body length of an adult is up to 15 cm. This fish species inhabits the sandy bottom of small rivers and streams, where it digs holes, most often under driftwood and large stones. Both male and female have the same protective dress of sandy color with numerous dark dots; males have kept a coal-black courtship dress.
European blenny sleeper has kept a predator’s diet: it feeds on benthic invertebrates, fish fry and eggs, and also catches fishes of small species and river crayfishes of suitable size by rushes from the shelter.
This species spawns portions of eggs during the warm season. The male attracts the female to the shelter by his coloring and behavior: he blocks the female’s path, shuddering with his whole body and displaying to the female his widely spread pectoral fins. Spawning takes place in a shelter, after which the female leaves the clutch. The male protects the eggs from predators, and directs the flow of water to the clutch, bending his body and straightening his fins. There are up to 200 eggs in the clutch; incubation lasts up to 2 weeks. Also, the male guards the larvae until they turn into fry and begin to feed actively. Sexual maturity comes in the second year of life; life expectancy is up to 10 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Snakehead river sleeper (Percchanna percchanna)
Order: Percoid fishes (Perciformes)
Family: Freshwater sleepers (Odontobutidae)
Habitats: central and eastern Europe, east to the Ural Mountains; any permanent reservoirs with stagnant or slow-flowing water.
In its Far Eastern homeland, Chinese sleeper (Perccottus glenii) was in the shadow of its distant relative – the northern snakehead (Channa argus) and occupied its own modest ecological niche. However, in Europe, where Chinese sleeper was introduced and successfully acclimatized, the ecological niche of the snakehead was empty, and in the Neocene, one of the descendants of the Chinese sleeper, who successfully survived the anthropogenic crisis and the Holocene-Neocene extinction, managed to occupy it. A descendant of the Chinese sleeper in warm freshwater reservoirs is a large predatory snakehead river sleeper. It is a fish reaching a length of one meter and weighing up to 10 kg (usually almost three times smaller), having a gray-green coloration with small specks (males in courtship dress are coal-black), smaller unpaired fins, and a more slender body compared to the ancestor. The mouth is oblique and semi-superior; in attacking fish, the mouth stretches into a short, wide tube that sucks prey in. This species is not picky in the choice of food and feeds on any aquatic organisms of suitable size – invertebrates, fishes and amphibians. Large specimens, on occasion, also eat small mammals and waterfowl, especially juveniles. True snakeheads, due to their teeth, can tear prey apart, while the snakehead river sleeper swallows it whole due to its extensible jaws. Snakehead river sleeper has no major enemies in its habitat, and cannibalism is the main limiting factor. Occasionally there are reservoirs in which only this fish species lives. Like its ancestor, snakehead river sleeper is extremely unpretentious, endures partial drying of the reservoir, and, if necessary, can cross small areas of land, especially at night. The fish has the ability to absorb oxygen from the water through its skin, and can also rise to the surface and pass air through its gills, aerating the water in the reservoir at the same time. In a drying pond, fish can dig into the ground to a depth of up to 1 meter, sometimes arranging collective shelters, where fishes secrete a common protective cocoon of slime that glues bottom sediments into a solid crust.
This species spawns eggs in portions throughout the warm season. A male in courtship dress attracts females to its shelter for spawning – usually to a large snag or to a hole in a steep clay riverbank. There are up to 200 large reddish eggs in the clutch. The male incubates it in his mouth, aerating if necessary. On hot summer days, males with eggs hide in thickets of amphibious plants, and under the cover of leaves and stems rise to the very surface of the water. Young fishes reach sexual maturity at the 3rd year of life. Life expectancy reaches 50 years.

This fish species was discovered by Kazimir Adamovich, the forum member.

Swamp skinflint (Harpagocottus endurans)
Order: Percoid fishes (Perciformes)
Family: Freshwater sleepers (Odontobutidae)
Habitat: Siberia, swamps, lakes and rivers.
In the human era, an incredible success in the struggle for existence was displayed by Chinese sleeper (Perccottus gleni), widely settled by people throughout Eurasia. In new habitats, it has proved to be a hardy and competitive species, easily superseding the local fauna and enduring extreme conditions of existence. After the human disappearance, this species continued to exist, and only the ice age forced it to retreat to warmer latitudes. After the warming of the climate, the descendants of Chinese sleeper from the rivers of the Far East settled widely in Siberia, occupying a variety of ecological niches.
Swamp skinflint belongs to large fishes – the body length in adults exceeds 150 cm. This is a bottom-dwelling fish species that prefers to hide among thickets of plants and snags. Often adult fish hide among the trunks in the thickets of swamp larch. The coloration of its body allows it to perfectly disguise itself among vegetation: the general color is brown, beige with a yellowish tinge on the belly; there are dark green or yellowish marble spots on the sides that form indistinct vertical stripes. In young fishes, the transverse striping is more pronounced and the coloration is more contrasting.
Pectoral fins are wide and rounded. Unpaired fins are shifted to the rear of the body. Tail fin is forked with a shallow notch and rounded tips of the lobes. Dorsal fin is equipped with eight pointed spines, well developed in young individuals – this is their main mean of protection from predators, including from adults of their own species, who are indiscriminate in food. There are also 2-3 strong spines in the anal fin.
Swamp skinflint is an ambush predator, preferring to stay in the lower layers of water and at the bottom. It catches prey with quick rushes from an ambush, but is not able to chase it for a long time. The muscles contain a significant amount of fat, which provides buoyancy and partly plays the role of antifreeze. The body is elongated; the large broad head makes about a quarter of the total length of the fish. Eyes are large, yellow or orange. Mouth with thick lips is able to open wide and stretch into a tube, sucking prey in. Teeth are numerous and slightly curved back. Fish lacks lateral line – it is a common feature of the family. Numerous taste buds are scattered over the body covers, allowing it to determine the presence of prey even in muddy dirty water.
The diet of this species includes any animals that this fish is able to swallow – from worms and small fish to ducks and rodents. Large individuals of the swamp skinflint are able to attack even geese (hence the name: “skinflint” means “greedy person”). Because of the piercing teeth, the fish is unable to bite off the piece of prey, so it swallows it whole.
Thanks to its endurance and resilience, swamp skinflint managed to settle across a significant part of the reservoirs of Northern Asia in the conditions of continental climate with hot summers and frosty winters. In summer, in stagnant reservoirs, fish can easily survive in dirty water, where plant material rots and there is almost no dissolved oxygen. Fish can emerge to the surface and take air by mouth, absorbing oxygen through the mucous membranes of the mouth cavity. In the south of the continent, such an ecological niche is occupied by giant snakeheads. The existence of the swamp skinflint appears to be possible because the cold and freezing of reservoirs do not allow snakeheads to settle to the north.
At the onset of cold weather, swamp skinflint buries itself into the ground or hides in deep non-freezing pools, secreting a layer of slime on its skin. Fish can easily endure the freezing of the body covers, and young fish can endure freezing into the ice and can even settle with floating ice floes.
After the snow melts and the reservoirs flood, the spawning season begins in the swamp skinflint. This fish species is strictly monogamous, spawning in shallow waters. By the time of spawning, the male gets a distinct courtship dress. The body color turns almost black, only slightly lighter at the edges of the fins. The iris of the eye becomes golden, and a large fatty outgrowth develops on the forehead and nose bridge. Attracting the female, the male performs a complex courtship ritual – he clears an area of the bottom from debris with strong lateral movements of his body, pushes the female to it and circles around her, spreading his fins and shaking his whole body. He accompanies his movements with a prolonged chirping. The established breeding pair of fish digs together a hole up to one meter in diameter, and spawns eggs – up to 3-4 thousand large eggs – in it. After spawning, the female swims away, and the male shows selfless care for the offspring – he protects the eggs for 20 days, driving all living creatures, up to waterfowl, away from the nest. After the offspring begins swimming, the male leaves the nest.
Growth is very slow: sexual maturity comes only at the age of 6-8 years, with a body length of about 50 cm. This is compensated by a significant life expectancy – over 120 years.

Reed goby (Calamogobius striatus)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: coastal reed thickets of Fourseas.

Picture by Tony Johnes

In Neocene in territory of South-Eastern Europe the huge brackish reservoir – Fourseas – had appeared literally from nonexistence. Waters of glaciers had thaw in early Neocene, and flowing of European rivers had formed it. Having filled in hollows of former Black, Azov, Caspian and Aral seas, this reservoir isolated from the ocean renders strong influence to the climate of western part of Eurasia.
Descendants of some survived European species of fishes inhabit Fourseas. They mainly belong to gobies though in ichthyofauna there are also representatives of other fish families. Fourseas became original “laboratory” of nature: here there is a process of active speciation of gobies, which could occupy various habitats. Among them there are ground predators and hunters for invertebrate, and also various pelagic forms.
The reed goby is one of species inhabiting Fourseas. This fish lives in coastal reed thickets, bordering by wide strip northern coast of Fourseas. The reed goby has perfectly adapted to such residence: it is unpretentious to salinity of water, easily tolerating complete desalination, steadier against lack of oxygen and undemanding to cleanliness of water, surviving even in brown stinky slush among rotting plants. And its appearance and habits literally permit this fish to merge with environmental plants and to become completely imperceptible both for predator, and for catch.
The body of reed goby is long, narrowed to the tail, and rather thick. The length of adult fish may reach 20 cm (male is larger than the female). The fish spends the most part of time, having attached to stalks of plants vertically. The reed goby uses for this purpose abdominal fins which at all species of this family are joined and transformed to strong sucker. Pectoral fins with strong fleshy bases permit to keep for the near stalks.
Living in such conditions, the fish has got excellent cryptic colouring: on brown background there are longitudinal yellowish strips. But masking is not unique protection of the reed goby: spikes of the first back fin are well advanced, and in them ducts of poisonous glands pass.
This fish is a predator eating fry of other fishes and various invertebrates: larvae of insects, crustaceans and leeches. Mouth of the reed goby is rather wide, and the fish can easily seize catch almost in half of its own length. Jaws of the reed goby are supplied with sharp teeth. Eyes of this goby are large and mobile; they provide to predator the full circular field of view.
In spawning season (in the middle of spring) the mouth of this goby turns from fatal trap to cradle: the male incubates eggs in mouth. This is preceded with complex courtship ritual during which males fight for the female, seizing each other by jaws and trying to expel the contender from the territory. The winner male begins courtship: it changes color (becomes almost black with longitudinal white strips), and “sits” on stalk of reed near to the female, showing to her opened fins. The female turns pale and compresses fins as a sign of submission. After that the female spawns eggs, and the male fertilizes it and takes in mouth for incubating. Within two weeks while there is an egg incubating, the male behaves very cautiously and secretively: it eats of nothing, carefully hiding in reeds. Larvae spend in his mouth about two - three days, and then turn to fry and leave a mouth of the father. This goby does not protect fry, and many young fishes become victims of water insects. At these fishes the cannibalism also is advanced.
Life expectancy at this species can reach ten years and more.

Pennonback goby (Vexillogobius hortulanus)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: Fourseas, thickets of water plants in estuaries of rivers.
Fourseas became the place of life of set of goby species related to each other, had evolved from several related species. They had survived in lower courses of rivers and brackish lakes formed in ice age at the place of Caspian and Black seas. During speciation at various species of gobies the adaptations, permitting to distinguish representatives of their own species from neighbors, had developed.
One species, at which such adaptations are especially well advanced, lives at sandy shallows, among thickets of eel grass and pondweed. This small fish is difficult for noticing, because usually representatives of this species of gobies dig in sand, waiting for catch: fry and large crustaceans. But if in field of view of hidden fish the congener appears, the lawful owner of territory warns it about its own presence: it opens the first back fin on which there are long fin rays and membrane forming bright “tag”. For such feature this fish is named pennonback goby. With the help of this fin the fish communicates with congeners, confidently distinguishing them among set of species of Fourseas gobies. It is the small fish: the length of body of the adult male does not exceed 15 cm, and the female is even smaller.
Body of the pennonback goby is lengthened, with thick tail and wide tail fin. Due to muscled constitution the fish is able to dig itself in sand literally by one movement. When dregs sediments, the fish appears practically imperceptible: from sand the tip of muzzle, protruding eyes and back jut out only. The back fin at this time is pressed to the body, and it is also imperceptible. But, when the noteworthy prey comes nearer to it, the goby makes sharp throw, snaps it, and instantly jumps in sand again.
The body of the pennonback goby has cryptic sandy colouring: on light yellow background a set of brown speckles is scattered merging to vague striped pattern. On back there is more speckles, and stomach of fish is almost completely white. Eyes of the pennonback goby also are perfectly disguised: the iris of the eye has the same pattern of speckles, therefore the hidden fish looks simply like continuation of sand. Pectoral, back and anal fins also have cryptic coloring.
But, if the goby will decide to warn contenders about its presence, it is difficult to not notice it. Back fin of this fish is very high: its height makes approximately half of common length of fish. Its forward part also has a cryptic “sandy” pattern, but the most part of “flag” at males has contrast and bright color: black with large white spots. On edges of fin the color changes from black to purple, and top and back edges are edged by bright red strip. Females have smaller “flag”, and in its coloring only black and white colors are combined.
This fish species is territorial: each fish occupies in the shallow water the certain site overgrown with water grasses, and zealously preserves it against strangers, showing if necessary bright back fin.
This goby spawns eggs in plants, and the laying is looked after by the male. He possesses the leading part in courtship ritual of these fishes. Spawning games take place in the beginning of summer, when water is warm enough. The male clears the chosen bush of dust and snails and tears out environmental plants so, that the bush appears surrounded with a strip of clean sand (a specific epithet “hortulanus” means “gardener”). After that courtship demonstrations begin: male entices females, showing them bright back fin. If the female has become interested, the male conducts her to the prepared plant. As a sign of absence of aggression the male “shivers” slightly lowered back fin. Courtship games pass roughly, being accompanied by “races” and easy lip biting. After all eggs (in clutch there is about 300 grains of roe) appear spawned, male expels female and starts to protect clutch. He preserves it against various fishes and large scuds, driving them away by impacts of head. Eggs develop about five - six days, then larvae swim out, and the male, having cleared a bush, starts to entice new females. For a season he takes part in spawning up to three times. Young fishes become sexual matured at the second year of life.
In winter when water at northern coast of Fourseas becomes cold, this fish leaves on depth and hibernates, having dug in sand. At this time pennonback gobies are inactive and form numerous congestions. In areas of rocky bottom fishes hibernate in deep cracks. At the southern coast of Fourseas pennonback gobies keep activity almost the year round.

Jabbering goby (Vermigobius loquax)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: deepwater areas of the Fourseas, depths up to 300 m.
After the end of the ice age at the turn of Holocene and Neocene, the rivers re-filled the almost dried-up basins of the Black, Azov, Caspian and Aral seas, forming a single brackish reservoir – Fourseas. But this reservoir, due to the geological processes that accompanied the collision of Africa and Eurasia, had no connection with the oceans, and its fauna was formed solely by the inhabitants of fresh waters and relict euryhaline species that survived in the few salt lakes suitable for life. With the return of the sea, they got a chance for further evolution and took full advantage of it. The main splash of adaptive radiation among the fishes of the Fourseas was given by gobies. The way to the niches of large predators, including pelagic ones, was closed for them – it was firmly “blocked” by sturgeons and descendants of pikes. But gobies produced a great variety of various filtrators and small benthic predators. Numerous species of gobies inhabited both shallow and deep waters of Fourseas. One of these species is the jabbering goby.
This species is a fairly large fish, resembling by its appearance deepwater Macrurus fishes of the human era. The body length of an adult fish is about one meter. The body is very slender, eel-shaped, with large broad head, tapering to a long (half the length of the body) tail. The coloration of the scaleless skin is dark gray, and the belly is lighter. Soft dorsal fin merges with the tail and anal fin into a single structure bordering the body. This species lives exclusively on the bottom, burying itself in soft silt with its tail, so the cloaca is shifted far forward, almost to the level of the base of the pectoral fins. The abdominal sucker is greatly reduced, leaving a fleshy pad of the base, bordered with reduced fin rays from the posterior edge. Usually, fishes of this species stay in vertical burrows, the walls of which are reinforced with slime, and grab food that appears at a short distance from their shelter. Less often, these fishes crawl in the thickness of the ground, wiggling like snakes, or swim over the very bottom. The disturbed fish instantly buries itself in the silt.
Life in the darkness of the depths of Fourseas has left its mark on the appearance and behavior of this species. This goby is called “jabbering” because of well-developed sound communication: if this fish does not hunt, then about every three minutes it emits a series of 5-6 short clicks, by which these fishes learn about each other’s presence. If a stranger enters the territory occupied by this fish, the series of clicks become longer. This fish is almost blind: its eyes are very small and distinguish only light from darkness. But on the other hand, this species has a very well developed chemical and, to a lesser extent, electrical sense. Jabbering goby is zoophagous and eats any food it finds – benthic invertebrates, fish eggs, small fish and carrion. A large dead fish that has fallen to the bottom is a very lucky find, and gobies from a vast territory gather around it. Biting the meat, they twist into the knots and tear off pieces that they can swallow.
These fishes have a pronounced seasonality in reproduction: fishes prepare for spawning in early spring. During the spawning season, males begin to utter half-minute long “series” of clicks. This is the way they call females and warn competitors about their presence. The female ready for spawning responds with shorter – 10 seconds long – series of sounds. This species spawns small eggs, which the male bears in his branchial cavity for several days without feeding. There are up to 100 thousand eggs in the clutch. In order to place it in the branchial cavity and fertilize it, fishes of both sexes have developed flexible tubular outgrowths of the cloaca, so the female lays eggs directly in the “incubator”, pushing her ovipositor under the male’s gill cover. Fertilization also takes place there. Juveniles of this species develop in the water column, feeding on bacteria, protozoans, and later on pelagic crustaceans. Fry of this species develop a large fin fold bordering the entire body, with thin needle-like outgrowths along the whole its edge. This feature helps to facilitate floating in the water column. At the age of 3 months, young fishes settle to the bottom, turning into a copy of adult fish.
This species grows and develops relatively slowly: sexual maturity comes at the age of 8 years and life expectancy reaches 60 years.

This fish species was discovered by Nick, the forum member.

Alpine waterfall goby (Gobiomyzon macrocephalus)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: Europe, mountain rivers of the Alps.
Favorable conditions for life established on Earth in the Neocene contributed to the growth of biological diversity in ecosystems. However, a side result of this process was increased competition, and as a consequence – natural selection directed towards deepening specialization. An example of the result of this trend is the genus of fishes living in the Alps – waterfall gobies, specialized for living in fast-flowing mountain rivers and waterfalls. Their typical representative is the Alpine waterfall goby – a fish common in rivers on the northern slopes of the Alps. The appearance of this species indicates the adaptation to life in fast-flowing water. This fish has a flat broad head and an expanded front part of the body; the head makes up to a quarter of the total length of this fish. The development of attachment devices is noteworthy: a sucker made of modified pelvic fins is developed on the chest, and the rays of the pectoral fins are equipped with small hooks that allow it to cling to the asperities of the stones. The outlines of the head and pectoral fins form a single disk. Pectoral fins have very large fleshy bases, allowing them to work as a single large suction disk. In the upper part of the gill cover, there is a valve that allows passing water over the base of the pectoral fin and does not let it to get under the body of the fish when breathing. When the fish fully opens its gill covers, water gets under the suction disc, and the fish detaches from the substrate. In their appearance, waterfall gobies resemble Gastromyzontidae fishes – relatives of loaches – a little bit, representing thus an example of convergent evolution.
The pelvic fins actually form a second “sucker inside the sucker”. With the help of this additional suction cup, fishes hold in place when the main suction disk does not work – for example, when the fish is eating or moving forward along the substrate. Due to muscle contractions, the suction cup from the pelvic fins can move slightly forward or backward. This allows the fish to climb up the waterfalls and stay on the rocks in a strong current. The body is of cylindrical shape; tail stalk is thick, with a wide fan-shaped tail fin.
There are two dorsal fins. The anterior (spiny) dorsal fin has turned into a signaling device – its rays are elongated, and it is catchy colored – yellowish-white with a black tip. The second dorsal fin reaches the edge of the tail fin.
The general color of the body is nondescript and changeable: usually the background is yellowish or light beige with dark spots of irregular shape on the back and sides. In various populations, the spots on sides can turn into small uniform specks, or form 4-6 “marble” vertical stripes on the sides.
Eyes are convex and mobile, sticking out above the surface of the “disk”, but if necessary, they can be drawn into the eye sockets. The mouth is wide; it can extend forward like a short tube. Thick lips with a small number of horny villi are able to scrape sessile insect larvae from the substrate. Waterfall gobies are zoophagous: they eat the larvae of mayflies and caddisflies, as well as other rheophilic invertebrates.
Interesting are the features of reproduction that allow these fishes to breed offspring successfully even in rapid streams of water. Males of these fishes bear eggs in a special “pouch” of two longitudinal folds of skin on the belly. Eggs are large and not numerous – up to 20-30 eggs in a clutch. Due to the low temperature of the water, they develop for a long time – up to 2 weeks. After hatching, the larvae keep in the pouch for about a month and feed on the male’s skin secretions. Having undergone metamorphosis, they leave the male’s pouch as fry ready for independent life, possessing a sucker and able to resist the current. Sexual maturity comes at the 6th-7th year of life; life expectancy reaches 30 years.
Related species live in the rivers of the Alps:
Domino goby (Gobiomyzon cataractobius) lives in a strong current in high-altitude areas throughout the Alps. Its body color is mottled – black with white markings on the sides; in local forms, the markings may merge into a longitudinal stripe on the side, or only one spot remains from them. This species lives in the fastest mountain rivers, often found on the almost vertical walls of waterfalls, where it keeps solely by its own suckers. The powerful suction disc is complemented by numerous villi on the underside of the body, which strengthen the adhesion to the substrate. Due to the developed suckers, fishes of this species can climb up waterfalls against the flow of water. The juveniles of this species often drift to the calmer lower reaches of rivers, but as their suckers grow and develop, the fishes rise upstream, simultaneously settling to other mountain streams. Fishes spend winter in ice-free streams under large stones, gathering for the wintering in groups of up to 10 or more individuals.
Southern waterfall goby (Gobiomyzon crassilabius) from the southern slopes of the Alps differs from related species by its broad pectoral fins: the head and pectoral fins make up about half of the total length of this fish. The upper lip is thick, protruding forward, with well-developed villi. The coloration is mottled: dark spots and light dots are scattered on the brown background. Belly and lower part of the disc are white with not numerous black spots. This species feeds mainly on algae fouling, underwater parts of plants of the riverweed family (Podostemaceae), as well as sessile larvae, and occasionally catches free-moving insect larvae.
These species are indistinctly separated from each other: there are numerous local transitional forms between them, combining the characteristics of nominal forms and capable of hybridization with neighboring forms.

Abyssal heterogobius (Heterogobius batophilus)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: Atlantic ocean, temperate latitudes, depth up to 2 kilometers.

Picture by Timothy Morris, colorization by Alexander Smyslov

At the boundary of Holocene and Neocene ecosystems of open ocean had suffered great losses because of “plankton accident” – sharp decrease of number and variety of plankton organisms caused by catastrophic changes in ecosystem of planet. As the result inhabitants of open ocean, and also species passed a part of life cycle in plankton had strongly suffered. Especially strong damage was put to deep-water fauna for which plankton and pelagic animals of top layers of water were a unique source of organic substances.
In Neocene become empty depths of oceans appeared populated again. Among the most successful immigrants in the world of depths there were gobies. These inhabitants of benthos moved down in depths along the continental slope, and then had developed pelagic habit of life already as deep-water animals. One of such gobies is the abyssal heterogobius living in Atlantic.
This species has received the name (literally meaning “the different goby”) because of sharp distinction in shape and habit of life of male and female. The female of abyssal heterogobius has the shape partly similar to shape of deep-water anglerfishes (Lophiiformes) of Holocene epoch. Its length is about 20 cm, from which the head with huge mouth amounts about third. The mouth of this fish is oblique upwards and can be extended to short tube – jaw bones of fish are connected by elastic membrane. Teeth of this goby are long, needle-shaped and bent hook-like – it is easy to keep catch by such teeth. Heterogobius eats pelagic fishes, octopuses and other invertebrates.
Eyes of the female of heterogobius are very small, and sight of fish is rather bad. Sight is practically useless at life in depth, but sharp sense of smell and rich circuit of lateral line channels advanced on head quite replace it to the female of heterogobius. Nostrils of fish are surrounded with thin leaf-looking outgrowths of skin dissected at edges. This adaptation considerably increases olfactory surface of nostrils. The body of fish is covered with naked slimy skin of grey color through which large blood vessels are visible. On stomach skin is thin and easily extensible, and through it interiors of fish are visible. The female of heterogobius can swallow catch of weight approximately identical with it.
Unpaired fins of female of deep-water heterogobius are short and rounded. Pectoral fins, on the contrary, are long (their length is approximately equal to the body length of fish) and fanlike. Having stretched them, fish passively soars in thickness of water, waiting for approach of catch. Fin rays are connected by thin delicate membrane.
The male of heterogobius considerably differs from the female by shape and way of life. It represents a creature about 2 cm long attaching to gills of the female. It sucks blood of the female and completely depends on it by way of feeding and development. Through blood it receives from the female hormonal signals about her physiological condition, and at the readiness of the female for spawning it produces sperm. The male is, in effect, the individual which early has stopped the growth. These fishes hatch from eggs having no gender, and the gender of maturing fish is determined by its subsequent life. The single individual always turns to the female. The growing female emits the special substance involving young individuals of this species in water. Using such trace young sexless fish searches the individuals turned to females.
The individual, managed to attach to the female turns to male under influence of hormonal signals coming from the blood. Hormones of the female suppress the “female” program of development of young fish, and it turns to male. Hormones of the female also suppress growth of the individual attached to it, and the male stays dwarf. Its contribution to reproduction is also important, but the maintenance of the high-grade large male in conditions of limited food resources is biologically inexpedient, and it turns to the true appendage on the body of the female, able only to breeding.
Hooked teeth of the male allow it to keep for the branchial arch of the female. In development the body of male deeply degenerates: in adult condition it is blind, lack of fins (from them only bristle-like rudiments of fin rays remain), and organs of lateral line also disappear at him. Gullet of the male turns out forward and sticks to gills of the female. This way blood of female does not get in water through branchial apertures of the male, and does not involve predators. Operculums of male are reduced, and at movement of the female water freely wash his gills. In such condition he is not able more to independent existence though it does not adhere to the female body as it was at deep-water anglerfishes of Holocene epoch.
Abyssal heterogobius bears eggs in mouth. Female regularly spawns portions of 300 – 400 eggs. The breeding cycle of this species is connected not to seasonal changes which are not felt in depths of ocean, and with physiological condition of adult female. Female at once grasps eggs laid in thickness of water in mouth and bears them in branchial cavity during 3 – 4 months, not feeding thus. At the moment of spawning male shows the certain activity: it bends body, penetrates into branchial cavity of female, and lets out soft roe, fertilizing eggs placed in mouth of the female. During the bearing of posterity the female grows thin. At this time she can reduce feeding of the male – blood vessel nourishing him grows thin and degenerates. It happens, that male not receiving an additional feed during the egg incubating of the female, perishes. But in this case any other young fish of suitable age and physiological condition can replace him.
The young growth leaves parental mouth, and leads independent life in top layers of water rich in forage. As young fishes grow, they settle deeper.

Lilliputian symbiogobius (Symbiogobius lilliputianus)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: reefs of the tropical zone of the Indian Ocean.
Gobies have relatively successfully survived the period of ecological crisis at the turn of Holocene and Neocene. A number of local species and inhabitants of coral reefs became extinct, but in the early Neocene, these fishes quickly regained their diversity and range. Species leading an unusual lifestyle and adapted to very specific conditions of existence began to appear among them.
Large bivalve mollusks living at the reefs of the Indian Ocean represent an excellent habitat for a variety of symbiotes and parasites that form a close community with their host. Among the settlers of the mantle cavity and gills of these mollusks, there are even fishes of several species. One of these species is the dwarf goby, which often lives in the shells of the “blossoming” tridacna. This is a lilliputian symbiogobius adapted to life exclusively under the protection of a large mollusk.
It is a very small transparent fish – its body length is up to 3 cm. The body of the symbiogobius is elongated, wormlike and very slender – its depth and thickness do not exceed 3 mm. Pigmentation in this species appears only at an early age, before the young fish finds a suitable host. In adult fish, the body is completely transparent, yellowish in color; bones and insides are clearly visible through the skin. The unpaired fins (except the first dorsal one) have merged into a single structure bordering the whole body; the fin rays are significantly reduced. The spines of the first dorsal fin lack a membrane between them. Pectoral fins are short; pelvic ones have merged into a powerful sucker located almost on the throat.
The eyes of this fish are convex, but small, located in the upper part of the head. Lilliputian symbiogobius has already begun the reduction of photosensitive retinal cells, among which cells with fatty inclusions gradually appear. Instead of vision, this species developed a keen sense of smell, and tassels of dermal villi covered with sensitive cells appeared near its nostrils.
The mouth of the symbiogobius is superior, equipped with thin pointed teeth and able to extend to a short tube. Feeding fishes scrape detritus, organic residues, dead areas of epithelium and parasites from the surface of the body of the host mollusk with their lower jaws. Also, symbiogobius hunts planktonic animals that get into the shell of the host mollusk with a current of water. If there is a lack of food, these fishes can damage the tissues of the host mollusk by attaching on its gills and sucking out a small amount of its blood, thus becoming semi-parasites.
This species settles in the shell in pairs or a small harem. The dominant individual is the larger male, and the remaining individuals are females. The sex of these fishes is not determined genetically and depends on the confluence of life circumstances. The stronger individual that settled the shell becomes a male, and the others develop according to the female type and reproduce normally. At a young age, this fish can easily change sex, but in old age, this ability decreases: the fish cannot complete the transformation to the end, becoming a sterile hermaphrodite. So there is a kind of selection and withdrawal from reproduction of “loser” males who lost in the struggle for the place of the leader of the group. They begin to behave like females, but they cannot take part in reproduction in full degree, and other females lay eggs for the new leader.
In this species, the male only fertilizes the eggs, and the females brood them. A clutch numbering 10 to 15 eggs is incubated in the mouth cavity. When the offspring hatch from the eggs, the female holds it in her mouth until their yolk sacs resolve and releases the already formed fry. During the year, the female rears up to 5-6 broods.
Through the exhalant siphon, the fry leave the shell and live on the reef for a certain time. At this time, they have a striated coloration and normally developed eyes. As they grow up, they retain many juvenile traits, including poorly developed bone tissue of the fin rays. When the fry finds a suitable host mollusk, it undergoes a rapid metamorphosis and acquires the features of an adult. Its development occurs according to the male or female type, depending on the number of individuals who have settled in the shell. Sexual maturity comes at the age of 3-4 months, and life expectancy does not exceed 2 years.

Blood-barbed goby (Prolongogobius sanguineobarbus)
Order: Percoid fishes (Perciformes)
Family: Gobies (Gobiidae)
Habitat: reefs of the tropical zone of the Indian and Pacific Oceans.
Fish are perhaps the only group of vertebrates whose representatives have repeatedly switched to a parasitic lifestyle. Among other classes of vertebrates, parasites are represented exclusively by several blood-sucking species. Among the fish of the Neocene, both parasites and semi-parasites are found, displaying various stages of transition to parasitism.
At the reefs of the Indian and Pacific Oceans, one fish species leading a semi-parasitic lifestyle can be found. Its hosts are large species of holothurians living in shallow water. When the situation around is calm, a red brush-like outgrowths protrude from the rectal openings of some holothurias. It is a part of the body of one of the inhabitants of the intestine of the holothuria – the blood-barbed goby. This small fish, with its appearance and lifestyle, demonstrates an amazing degree of adaptation to such an unusual habitat.
Blood-barbed goby is a wormlike fish about 10 cm long. It has a translucent body having no pigment cells. The unpaired fins are greatly reduced: the second dorsal one, tail and anal ones represent simply a unite skin fold bordering the body of the fish. The first dorsal fin is reduced to five small flexible spines growing just behind the head. The body coverings are dense, covered with abundant slime – this feature helps the fish to penetrate into the intestine of the host animal and avoid damage by the feces of the holothurian that consist mostly of sand.
The pelvic fins are transformed into a strong suction cup shifted forward to the throat. It is the main attachment organ, important for the lifestyle of this fish.
The head of the blood-barbed goby is deep, but short and strongly compressed from the sides. The eyes are small and located at the top of the head. The vision of this fish is very poor: the reduction of the visual elements of the retina has begun, and the fish only distinguishes the outlines of objects in good light.
In connection with living in the body of another animal, the ancestors of this species faced the need to rebuild the respiratory system. As a result, this species has developed an unusual breathing device that gives the fish an unusual appearance. The gills of blood-barbed goby are reduced, but the gas exchange function was taken over by a highly stretchable skin outgrowth on the lower jaw, which tip resembles a beard of red hairs (hence the name of this fish). Its surface is covered with epithelial villi and numerous chemical sense receptors, cells of a special branch of the lateral line and even photosensitive cells. Blood vessels abundantly permeate this outgrowth, giving it a red color. The “beard” of this fish can extend to a distance equal to half the length of the fish itself.
Usually the fish keeps inside the holothuria in its rectum, attached to the intestinal wall of the animal near the anus. It can leave the intestines of the holothuria to catch prey, but usually sticks out only its “beard”. With the help of this outgrowth, the fish breathes and even partially receives information about the environment – in particular, about the presence of prey or predators and the movements of water outside. The wholeness of the “beard” is very important for this fish, so the damaged “beard” regenerates quickly. But usually at the first sign of danger, the fish draws the “beard” in to itself.
Blood-barbed goby feeds on small invertebrates, which it catches by rushing out of its hiding place. Its mouth is equipped with two “brushes” of numerous small teeth growing on the tips of the jaws. The mouth cut in this fish is almost vertical, and the lower jaw is directed straight up. If there is not enough prey, the fish begins to feed on the tissues of its host, scraping the epithelium from the intestinal walls of the holothuria with its “brushes” of teeth. This action does not cause much damage to the holothuria, since the animal has a good ability to regenerate. The only danger for the blood-barbed goby is the ability of some holothurians to eject their insides in case of danger. Then the fish can easily become prey to a predator attacking the holothuria. But in such cases, the fish often manages to get free quickly and swim away. The blood-barbed goby can live for some time outside the body of the holothuria, but searches actively for a host by smell and at the first opportunity settles back into the body of the holothuria.
This fish species is a hermaphrodite, but for fertilization it is important to have two unrelated fishes that mutually fertilize each other. The fish bears a clutch of 50-70 small eggs in the mouth and releases fry in a week. After spawning eggs, several fertilized egg cells, which do not turn into true eggs, remain in the oviducts of the fish. If the new fertilization didn’t happen, the unfertilized eggs resolve quickly, and the egg cells divide into several new ones and further develop as normal eggs. Thus, the offspring of a fish can consist entirely of identical twins of several variants. If fertilization has occurred, the fertilized eggs remaining from the previous clutch simply develop into normal eggs, and there are always several fry from the previous father in the new brood. And then the eggs of the new clutch remain as “spare” ones.
The fry of the blood-barbed goby lead a non-parasitic lifestyle and feed on microscopic invertebrates. With a length of about 2 cm, the young fish begins to search for a host from among the young holothurians.

Firebeard (Telescopiophthalmus luciobarba)
Order: Percoid fishes (Perciformes), suborder Gobioidei
Family: Abyss gobies (Abyssogobiidae)
Habitat: Atlantic, temperate and cold waters of the northern hemisphere, depths up to 3000 meters.

Picture by Tim Morris, colorization by Alexander Smyslov

The “plankton catastrophe” at the turn of Holocene and Neocene affected not only the inhabitants of the upper layers of water. Deep-sea animals, the existence of which was based mainly on the intake of food from the surface layers of the ocean, suffered from it to a much greater extent. In the early Neocene, fishes began to settle into the depths of the ocean again. Some of these fishes did it from the upper layers of the water, but some ones “descended” along the continental slope and turned into inhabitants of the oceanic bottom or turned to secondary pelagic species. Among deep-sea fishes there are descendants of gobies (Gobiidae), which have formed several independent families of deep-sea predators.
Firebeard is a pelagic goby species and lives in the water column far from the continental slope and seamounts. The length of an adult rarely exceeds 20 cm. Its appearance bears many features characteristic of the abyssal inhabitants. It has thin translucent skin, flabby muscles and very flexible bones with a small amount of minerals. The body of this fish is shortened compared to the ancestral forms from shallow water; tail stalk ends with a fan-shaped fin. Dorsal fins are reduced: the spiny dorsal fin has lost its membrane and turned into several separately growing spines. The soft dorsal fin is rounded, shifted back to the tail. A long spike grows in the anterior part of the anal fin.
Pectoral fins are very well developed: they represent the main organs of the movement. They are fan-shaped, and their bases are equipped with strong muscles that attach to the overdeveloped bones of the pectoral girdle. The pectoral fins are shifted upwards and work as a kind of “wings”, allowing this slow-moving fish to swim short distances. Pelvic fins, shifted to the throat, have lost the sucker function characteristic of the shallow-water ancestors of this fish. The membrane between the fin rays is greatly reduced, and the rays themselves have turned into an organ of bioluminescence. The pelvic fins of this fish look like a “beard” with elongated rays, which also facilitate floating in the water. At the tips of the rays, there are luminescent organs – teardrop-shaped sacs inhabited by symbiotic glowing bacteria emitting a blue glow.
The head of the firebeard looks very bizarre. This fish has good eyesight and large telescopic eyes that can turn back and forth at an angle of 90 degrees – from an almost vertical position to a horizontal one. Behind the bases of the eyes are small luminescent organs that produce red light. The mouth of the firebeard is wide, and the jaw bones are connected by extendable ligaments and can move apart strongly when the fish swallows large prey. There are many thin sharp slightly bent back teeth growing in the jaws; the teeth in the front of the mouth are so large that they protrude more than half out of the closed mouth. The ability to swallow and digest large prey is vital for deep-sea fish: prey is rare in its habitat. The abdominal wall and stomach of firebeard are highly stretchable – the fish easily swallows prey the size of itself.
Firebeard is a bad swimmer: the fish prefers to float in the water column, spreading the rays of the pelvic fins to the sides and occasionally flapping the pectoral fins to keep the balance. Luring its prey, the fish “plays” with its fin rays, and so its baits mimic the movement of a cluster of small animals. Having felt the approach of prey, the fish “turns on” the red luminescent organs, that help it to notice prey, which can often be colored red.
The male of this species is smaller than the female, so courtship proceeds very carefully. The male swims at a respectful distance around the female, emitting an odorous slime that allows the female to identify him as a congener. Courtship includes the display of the luminescent organs and the male’s touchings of the female’s back. During the courtship, a portion of eggs matures quickly in the female’s ovaries (usually there are several portions of eggs in each ovary at various stages of maturity). The female spawns the eggs directly into the water, and the male fertilizes them and immediately takes them into his mouth and begins to incubate. Incubation lasts up to two weeks, and about the same time the offspring develops in the male’s mouth cavity. All this time, the male does not eat anything.
The growth of this species is very slow: at about the age of five, fishes reach sexual maturity. Life expectancy reaches 30 years or more.

Horned sea bulldog (Bathymastiffus cornutus)
Order: Percoid fishes (Perciformes), suborder Gobioidei
Family: Abyss gobies (Abyssogobiidae)
Habitat: Atlantic Ocean, depths up to 2000 meters, water column.

Picture by Tim Morris, colorization by Alexander Smyslov

The “plankton catastrophe” of the turn of Holocene and Neocene caused deep changes in the composition of the pelagic fauna both in the upper water layers and in the meso- and bathypelagic zones, as well as in the abyssal zone. Deep-sea animals are just as dependent on plankton productivity as the inhabitants of the epipelagial zone. As a result, the Neocene fauna of deep-sea animals is largely represented by new groups of animals.
Sea bulldogs form a group of deep-sea fishes, descendants of gobies that migrated to the depths of the ocean after the mass extinction of deep-sea fish. They have gone through a long enough path of evolution and developed features characteristic of the inhabitants of the depths.
Horned sea bulldog is a medium-sized fish: the length of an adult is about 30 cm. It has a disproportionately large head: more than a quarter of the total length of the fish. A significant part of the head is made up of jaws that can open wide and extend strongly due to elastic connective tissue ligaments – it is an adaptation for feeding on large prey. The upper jaw is shorter than the lower one; elongated teeth in the front of the lower jaw protrude from the mouth of the fish. The eyes are located at the top of the head; they are very small, protected from above by leathery horns, at the tips of which luminescent organs are developed. Another luminescent organ is present on the lower surface of the upper lip of the fish. Luring its prey, horned sea bulldog opens its mouth and lifts its upper lip, making this glowing organ more visible from afar. When prey approaches, the fish lowers its lip and slightly highlights the inside of its mouth, equipped with a silver lining. The luminescent organs on the horns serve mainly for intraspecific communication.
Pelvic fins of this fish are fan-shaped. Their bases are fleshy, mobile and shifted upwards. The fish moves in the water column and makes turns due to synchronous or alternating flaps of its pectoral fins. The sucker formed by the fused pelvic fins and characteristic of ancestral forms is greatly reduced in sea bulldogs – only some thin cartilages remain in the thickness of the musculature, indicating the former presence of pelvic fins.
The spiny dorsal fin turned into several long, thin spines. The soft dorsal fin fuses with the caudal and anal fins into a single structure bordering the body – the fish resembles a huge tadpole with fins.
The skin of sea bulldogs is scaleless and has most often a reddish-brown color. The skin on the belly is very stretchable: the fish is able to capture and swallow prey equal in weight to the predator itself.
Reproduction in this species occurs in the water column. The female is smaller than the male, and her role in reproduction is reduced only to spawning eggs. Spawning is accompanied by bright flashes of lights on the horns above the eyes. The male shows the female its opened mouth, “highlighting” it with a glowing organ on the lip. This serves as a signal for the female to spawn: she spawns eggs directly on the teeth of the male. The cloaca in this fish is shifted forward almost to the throat, so the female does not swim too far into the mouth of the male. When she lays down the last portion of eggs, the male “shakes” her off and releases the soft roe. Swimming in a cloud of his soft roe, he fertilizes the eggs and carries them on his teeth for several weeks. All this time, the male does not eat anything and ventilates the eggs with movements of the jaws and gill covers. He carefully disguises himself, spending most of the time in immobility and extinguishing the luminescent organs.
The offspring leads a pelagic lifestyle, luring prey (small invertebrates) with the help of smell.

Seal mudskipper (Batrachophoca gigantea)
Order: Percoid fishes (Perciformes)
Family: Mudskippers (Periophthalmidae)
Habitat: Hawaii, littoral zone between reeves and the coast.

Picture by Fanboyphilosopher

Mudskippers are fishes unusual in many respects. By their way of life they show that fish is capable to develop even the environment atypical for its ancestors, if it will have no competitors. They have occupied mangrove swamps – a specific inhabitancy in which they did not have competitors, because amphibians do not suffer salt water. Mudskippers became very similar to frogs in some features of appearance and behaviour, but all the same they still are fishes. In epoch of late Holocene congelation many species of these fishes had died out, as the climate became much colder, and the areas of mangrove swamps, suitable for inhabiting of these fishes, had been reduced. Mudskippers had survived only in Southeast Asia where areas of mangrove forests had kept.
In early Neocene active adaptive radiation and settling of descendants of few survived species of these fishes had begun. Mudskippers had began to develop newly forming mangrove forests actively. One species of these fishes had developed an interesting way of settling – it began to settle on floating trunks of trees. In parallel this species had developed the ability to brood eggs in mouth that had allowed it to “tear off” the coast completely and to turn to true sea traveller. Descendants of “wandering” mudskippers had settled mainly at the islands of tropical zone of Pacific Ocean to the south of equator. In northern hemisphere they had only one successful attempt of settling, but these fishes had mastered this opportunity in fullest degree: they had occupied Hawaii. Development of new extensive habitats was accompanied by active speciation, and as a result of it some related species of these “amphibious” fishes differing from each other in behaviour and ecology live at the coasts and reeves of Hawaii.
Due to protruding eyes and the propensity to live at the shoaliness these fishes are very similar to frogs externally. But nevertheless one of species of Hawaiian mudskippers is difficult for confusing with frog: this is a true monster of about one meter long, weighting of 25 kgs, the largest species of mudskippers ever living on the Earth. It is possible to confuse from afar these animals laying at the sea shoaliness with small seals; therefore they are named seal mudskippers. Their name Batrachophoca means “frog seal” and precisely reflects the appearance and habits of these creatures. Seal mudskipper is too heavy to jump; therefore it simply creeps at the littoral zone with the help of strong pectoral fins, helping to itself with pushes of tail. And its glittering slimy skin and head with wide mouth and protruding eyes give to it any similarity to frog. But operculums and fins normally advanced at this one precisely specify it as a fish.
Seal mudskipper has very big head with wide mouth and strong jaws. Above thick upper lip two fleshy short wattles directed down stick out. The male’s head is very large and looks disproportionate relatively to forward part of body. On male’s nape there is a pair of bone lumps which are used in courtship tournaments.
This fish is a predator like all its relatives. Due to sharp sight this huge mudskipper notices dangers in good time and hides in water. And mobile golden eyes with round pupils, sticking out at top of head, provide to it the complete circular field of view. Under water this fish also searches for prey with the help of sight. The jaw grip at eal mudskipper is very strong: this predator can easily splinter head of fish about half meter long by one bite and swallow it entirely.
The lengthened body of seal mudskipper is dimly colored: on brownish-olive background dark grey irregular-shaped spots are scattered; on back they are more numerous, than on stomach. It makes fish not too appreciable from apart. But the seal mudskipper not always needs to be imperceptible: each fish of this species occupies the certain territory and protects it from relatives. For the prevention of territorial conflicts fishes display visual signals to each other if the border of territory appears broken. For this purpose fishes use first back fin appreciable from apart. It is high, has short basis and is similar to flag in colouring – on white background large black spots are scattered. Raising this fin vertically, fish signals to contenders that the territory is occupied. At males back fin is higher, rather than at females, and there are more spots on it. In near fight fishes use one more means of intimidation of the opponent: conflicting fishes stretch in sides and completely straighten operculums. Then red spots on white background become appreciable; they are located on soft tissues and at quiet fish are hidden in skin plicas. If demonstrations had not conceived effect, fish expels the contender from the territory by impacts of head and tail.
Seal mudskipper eats all species of animals which can be found in littoral zone. It has a special way of getting of food, effectively using opportunities of the changeable habitat. This fish differs in complex building behaviour: each seal mudskipper builds for itself deep hole for life, surrounding it with bank of stones and sand. During the inflow fish creeps away from hole to the shoalinesses where it lays, having put out from water half of body, and displays back fin to contenders. In addition to the living hole of about half meter depth, fish makes in the territory some trap holes of about one meter depth. During the outflow fishes, crabs and small octopuses had not time to leave littoral zone gather in them. Seal mudskipper eats them: during outflow seal mudskipper creeps from one trapping hole to another, renews them, pulling out stones fallen inside by mouth and re-building their walls. Also it catches the fishes and other sea animals caught in trap.
The courtship season at these fishes stretches for all year. As a rule, around of male’s territory there are some sites where females live. The female at this species is smaller, rather than male, and her head is not so large. The female ready to spawning creeps to male’s territory, expressing the submission by her pose: she keeps back fin lowered to back, and makes characteristic “nodding” movements by head. Male displays to her the force and the good physical shape, having opened a back fin, having inflated operculums and having risen on strong pectoral fins. If male can not keep such poses for a long time (that means it is weak physically), female starts to rise back fin in reply to his court, displaying thus the counter aggression and unwillingness to submit. Such continuation of ritual can result in transient fight, and the female returns to her territory.
Well advanced male, having shown the physical shape, invites female to follow him, pushing her by sides to the living hole. Here female spawns very large eggs; male fertilizes them and at once takes in mouth. In clutch of this species it may be up to 300 yellowish eggs of small cherry size. Brooding eggs, male eats of nothing and becomes very aggressive. In posterity brooding time its colouring changes: head blackens, and spots on back fin become larger. It rushes on any of the relatives appeared nearby, and strikes them strong impacts by tail and sides. It happens, that male furiously attacks even the birds having rest in his territory.
The young ones hatch from eggs in one week after spawning. The first days of life young mudskippers stay in male’s mouth, while their yolk sac is resorbing. Then he lets them out in the living hole, and does not care of them any more. After brooding of posterity male is fattened for about one month, and starts courting the females again. For one year the spawning cycle repeats 4 – 5 times.
Young fishes search to themselves for shelter in a littoral zone – they frequently become prey larger congeners. To grow up to adult condition and to start spawning it is needed of about six years for young seal mudskipper. For this time the majority of fishes of this species becomes prey of various predators. Only quickness rescues them from various dangers, but the adult fish has almost nobody to be afraid due to size and ability to live in places where large predators can not reach. Seal mudskipper can live over 30 years.

Lono, or froggy mudskipper (Ranophthalmus lono)
Order: Percoid fishes (Perciformes)
Family: Mudskippers (Periophthalmidae)
Habitat: Eonesia, Fisaga Islands; tropical forests.
The islands of Eonesia, which rose from the bottom of the Pacific Ocean in the Neocene, became a place where nature set up an amazing evolutionary experiments. They had been populated exclusively in a natural way, and bizarre ecosystems were formed there. The descendant of the mudskipper living on the Fisaga Islands represents another attempt of fishes to conquer land – it is one of the most terrestrial fish species of the Neocene Earth.
This species is named after Lono, the Hawaiian god of abundance, agriculture, rains and music; the full name of the god is Lono-nui-noho-i-ka-wai that means in Hawaiian language “Great Lono living in water”; it reflects the dual nature of this creature – a fish living on land.
This amazing green-colored fish has occupied a niche of tree frog tadpoles at the islands which frogs cannot colonize for natural reasons. And the size of the fish is also equal the size of a tadpole – the body length of an adult one is only about 30-35 mm. These fishes live on the leaves of trees, attaching themselves with sticky slime released from the pores on the belly of this fish; this slime resembles snail slime in consistency. However, unlike snails, fishes move faster, as they skillfully use their thickened paw-like pectoral fins, which are used as a support when moving. The froggy mudskipper has a round head with a wide mouth and large bulging eyes that can turn in different directions independently of each other. The anal fin has turned into several pointed spines; tail fin is shortened. The gills are complemented by a chamber with a folded epithelium – it is an additional organ of air respiration. Also, the fish receives a significant part of oxygen through its skin – due to its small size, it fully satisfies its oxygen demand in this way.
The slime with which the fishes are completely covered helps them not to dry out in the sun – it contains a significant amount of proteins that prevent moisture evaporation. However, the fishes themselves almost do not expose themselves to the direct sunlight: they prefer to hunt in the dense coastal forest for insects on the lower surface of the leaves. Their favorite food is butterfly caterpillars, from the invasion of which these amphibious fishes protect the island forests. But they also enjoy eating other insects, especially ants, which have settled even to the remote islands. Froggy mudskippers themselves fall prey of forest birds, land crabs and sawleg grasshoppers. And only the abundance and secrecy of these amphibious fishes saves them from extinction, as well as the abundance of their main food – caterpillars and ants.
Courtship games take place during the rain season. At this time, males attract females by stretching their dorsal fins of bright red color. There are also tournaments between males, especially if their territories are in the neighborhood. First, the males display their dorsal fins to each other. If their sizes are equal and it is not possible to identify the winner, the battle begins; the winner must tear the opponent off the leaf and throw him down. Then the victorious male courts the female, constantly stretching his fin, and then fertilizes the female, snuggling up to her. Fertilization is internal; the male guards the female until she spawns all the eggs. These fishes spawn fertilized eggs in small reservoirs formed in the axils of the leaves of large plants – palms and screwpines. Here the hatched fry feed on the larvae of insects living near them and grow slowly. If there are no suitable places for spawning eggs, the females lay eggs on the branches of trees in special foam nests, as in some species of tree frogs. The abundantly secreted slime is “whipped” to form a foam with the help of the mouth and gills, and a foam lump up to 10 cm in diameter is formed in a secluded place. Here the offspring behave differently: the fry feed on each other; it is possible, because up to a hundred eggs are laid in one nest. Usually only 1-2 individuals survive from such a clutch, which grow quickly and leave the nest with a body length of about 12 mm. They hide among the moss and grow intensively, feeding on small invertebrates. Sexual maturity comes at the age of 9-11 months, and life expectancy does not exceed 3 years.
This fish species was discovered by Wovoka, the forum member.

Sargassum large-toothed blenny (Algoblennius inconspicuus)
Order: Percoid fishes (Perciformes)
Family: Blennies (Blennidae)
Habitat: Atlantic Ocean, thickets of floating algae near New Azora Island.
In human time congestions of Sargassum algae (Sargassum) floating near ocean surface formed a favorable inhabitancy for various animals. Among these creatures it was possible to meet original descendants of shore animals living actually in open ocean.
At the boundary of Holocene and Neocene, when character of sea currents had changed, the quantity of floating sargassum algae has decreased because of cooling of ocean water. But in Neocene, after stabilization of conditions and global warming, fields of seaweed have again plentifully filled in the central part of Atlantic. They grow in huge whirlpool which is slowly “twisting” by warm Gulf Stream current to the north, and its cold “double” Anti-Gulf Stream flowing along the European coast to the south.
Thickets of floating algae are the specific environment: here it is not important to be able to swim quickly, but ability to creep and mask is very important. Therefore fishes living in this place, in the majority are very bad swimmers. But almost all of them are skilful masters of masking.
Sargassum large-toothed blenny is the typical inhabitant of floating algae. At it there is rather short and high body. General length of fish is about 20 cm at height up to 10 cm. The tail fin is almost joined with anal and back fins; it is rather wide and fan-shaped: it is the feature indicating that the fish swims reluctantly.
At this fish there are large head and big mouth slightly oblique upwards. Eyes of this blenny are directed forward: sight of this fish is three-dimensional. Eyes of sargassum large-toothed blenny badly distinguish colors, but are especially sensitive to movements: so it easily defines presence of small animals have hidden among algae. These features tell that sargassum large-toothed blenny is a gluttonous predator in the algae world. It is an ecological analogue of sargassum anglerfish (Histrio histrio) from the order Antennariiformes. And external similarity of these species is the result of convergence.
One more feature of similarity of this blenny with sargass anglerfish is the special structure of pectoral fins. They have expanded fleshy bases due to what can grasp sarments of seaweed. As a rule, the fish keeps in thickets, having pressed sarments of algae by fins to sides. In case of necessity of moving to small distance, the fish creeps among algae, moving them apart by fins, as if by paws.
Similarly to Holocene algae inhabitants, sargassum large-toothed blenny differs in original colouring including features of camouflage: its body is colored yellowish – grey and is covered with dark brown irregular-shaped spots. Above eyes of fish there are leaf-looking outgrowths of orange color with the rough white edges, simulating dying off parts of seaweed. In back fin forward beams are lengthened, on them there are separate skinny “tags” strengthening masking develop.
Sargassum large-toothed blenny is a solitary predator. Due to sharp teeth in forward part of a mouth it easily can kill fish or shrimp of half of its own length. Usually this fish waits catch, motionlessly sitting among seaweed, and “coming to life” when the possible prey will come nearer almost in an emphasis.
Each fish of this species suffers neighbours near to itself only in spawning season. Spawning at these fishes proceeds in couples. Male is larger than female; it also differs in brighter colouring and advanced outgrowths above eyes (frequently near large outgrowth there are some smaller ones). Usually male himself interferes in possession of females, and chooses to itself the spawning partner. Per one year there are about three clutches, usually the spawning occurs in the summer and an early autumn.
The strong parental instinct is peculiar to these fishes. At this species the male cares of posterity: it bears eggs in a mouth, touching and ventilating them. At this time it becomes more cautious, and hides in thicket of seaweed. The egg incubating (in clutch there are about two hundred rather large grains of roe) lasts about one week, and two or three days the young growth is hidden in mouth of the male. Later young fry leave its mouth, and next time they can return there only as a catch: the male does not care of fry, and at an opportunity willingly will to have eaten the neighbour of the smaller size.

Non-glowing bathycrystallichthys (Bathycrystallichthys unlucens)
Order: Percoid fishes (Perciformes)
Family: Blennies (Blenniidae)
Habitat: Pacific Ocean, depths from 500 up to 1000 meters.

Picture by Timothy Morris, colorization by Biolog

Various blennies were characteristic coastal fishes of Pacific Ocean. Some species of these bottom-dwelling fishes lived in cold “forests” of brown algae, and others preferred coral reeves. Wide area of family and high ecological plasticity had permitted this group of fishes to survive during mass extinction and to occupy forming ecosystems of early Neocene epoch. At the extinction of deepwater ichthyofauna after “plankton accident” blennies had started to develop ocean abyssal zone. Among them strange species like jellyfish blenny (Medusoblennius holopelagicus) had evolved. Some species of blennies had penetrated to deep water along the continental slope and as already true deep-water fishes had “taken off” bottom, developing thickness of water.
Rather large pelagic predator, non-glowing bathycrystallichthys belongs to blennies. It is a fish about 40 sm long with deep body, large head and pointed tail. Unpaired fins border the body of this fish as one continuous strip. Pectoral fins of bathycrystallichthys are fanlike; they have thin long fin rays and transparent membrane. Having stretched them, fish passively soars in thickness of water waiting for approaching of prey.
The body of bathycrystallichthys is absolutely lack of natural pigmentation and is translucent – if at the depth where this fish lives, there is a good lighting, through skin and aqueous muscles it would be possible to see its interiors and a skeleton.
Bathycrystallichthys has large head with well advanced jaws and big eyes. Very sensitive eyes of this fish catch the slightest flash of light emitting by deepwater animals. Like to almost all inhabitants of deep, bathycrystallichthys is a carnivore. Its teeth are thin and numerous; they jut out from mouth of this fish, even when the mouth is closed. Bathycrystallichthys eats various invertebrates, obviously preferring soft-bodied cephalopods and fishes. Occasionally this fish catches jellyfishes and swimming worms, but never hunts crustaceans.
Many fishes living in depths have their own organs of luminescence. They eitherr develop the substance luciferin which shines at the reaction with luciferase enzyme, or give a shelter to symbiotic luminous bacteria in special organs and use their ability to glow. Bathycrystallichthys is not able to glow independently and has no symbiotic bacteria. Nevertheless, it is not lonely during the hunt in depths. The success in attraction of prey at this species depends on strange symbiosis with special species of annelids, stomach lightworm (Gasteronereis luciferus). This worm is capable to glow very brightly, and its light, clearly visible through translucent body of fish, involves prey. The way of coexistence of fish and worm is interesting: worm lives partly in its stomach, having fixed by the back end of body for branchial arches of fish, as if by anchor. Prey is shared between symbiotes: part of forage had got in stomach is eaten by worm, and other part is digested by fish. If bathycrystallichthys eats large prey and swallows it entirely, worm does not suffer from it. It has firm covers of body, and does not endure inconveniences from existence in hardly filled stomach of fish.
Bathycrystallichthys had developed the original way of care of posterity: during spawning female pastes a cluster of small transparent eggs on chest and stomach of the male. He fertilizes eggs and bears them up to fry hatch. Young ones of these fishes develop in top layers of water. The probability of meeting of larvae of symbiotic worms, which attach to gills of young fishes and gradually develop, is greater here. Growing up young fish migrates to depth, and worm gradually starts to produce glowing substance. When the worm perishes for any reasons, fish starts to live half-starving and also can die: in depths of ocean the probability to meet larvae of stomach lightworm is close to zero.

The idea about existence of This fish species is proposed by Simon, the forum member.

European snakefish (Serpentozoarces europaea)
Order: Percoid fishes (Perciformes)
Family: Eelpouts (Zoarcidae)
Habitat: rivers and swamps of Central, East and North Europe, temperate and cold climatic zones.

Picture by Alexander Smyslov

Seas of North Europe underwent significant changes at the boundary of Holocene and Neocene. The congelation had held down the north of Eurasia by continuous ice cover, having buried under it Baltic Sea and coast of Northern Sea (in ice age the ocean level had decreased, and the sea had substantionally receded). Inhabitants of sea coasts had been compelled to adapt to changing conditions, or died out. The part of species had receded following the sea, and the another part had passed to life in fresh water of rivers and lakes. Among survived species there were various crustaceans and some fishes. When climate had changed again, these species had occupied new habitats already in new quality.
One of such fugitives from a glacier lives in fresh waters of Europe – it is European snakefish, the freshwater species of eelpouts. Ancestors of this fish had completely left the sea in glacial epoch at the boundary of Holocene and Neocene – they appeared are off from northern seas by coming glaciers, and compelled to adapt to inhabiting in fresh water. The majority of sea fishes can not make it because of problems in development of eggs and fry. But eelpouts had easily made it – they belong to viviparous fishes, and in their life cycle there is no the stage of egg sensitive to change of external factors. Therefore right till some millenia populations of eelpouts completely passed full cycle of development in fresh water had appeared in Europe.
The snakefish has kept features of appearance characteristic for its ancestors. It is a fish more than one and half meters long with reduced unpaired fins which edge its back and tail as a continuous narrow border. In forward part of back fin there are some spikes with poisonous slime serving for protection against enemies. Pectoral fins have fleshy bases, and fin rays are strong and elastic. With their help snakefish pushes from roughnesses of ground during the movement on land and makes the way through thickets of underwater plants.
The skin of European snakefish is naked, but covered with a layer of viscous slime. It prevents the drying when fish appears on land. Besides the skin of snakefish is penetrated with a circuit of capillaries, and through it fish receives a significant part of oxygen. Colouring of skin is spotty, green with black “marble” pattern; stomach is white.
Head of snakefish is flat and wide, with slightly bulging eyes and wide mouth. Teeth are pointed and thin.
Snakefish settles in marshlands where small reservoirs alternate with sites of land. The majority of fishes does not live in such places, therefore snakefish is almost out of competition. In summer reservoirs, in which it settles, may dry up. But snakefish is well adapted to such difficulties. It can easily creep overland, respiring with the help of skin. This fish creeps pushing by bends of body and helping itself by pectoral fins. Snakefish can creep within several days in searches of water. If weather is too hot, fish hides in shady place and may escape from heat even in holes of rodents.
Snakefish is a predator. In water it eats small fish, frogs and crustaceans. Frequently snakefish traps them in shallow water, having dug in ground, or having hidden among plants. Also this fish can catch sluggish insects, snails and earthworms on land.
This fish species has kept ability to vivipary had helped to survive to its ancestors till the ice age. Pairing at snakefishes takes place in autumn, and female hibernates, while in its ovaries the posterity develops. Young ones of snakefish receive an additional feed – products of secretion of female’s ovoducts walls. Due to it the posterity of snakefish is born already completely developed and ready to independent life. In spring when the high water comes to an end, the female gives rise to about ten large young fishes, reaching approximately one fifth of the length of female.

Snake-like wolffish (Anarrhichthys serpentiformis)
Order: Percoid fishes (Perciformes), suborder Zoarcoidei
Family: Sea wolves (Anarhichidae)
Habitat: temperate and cold waters of the North Pacific Ocean – the Sea of Okhotsk, from Kamchatka to southern Alaska.
In the Neocene, North America, moving westward due to the expansion of the Atlantic, connected with Eurasia, forming the Beringian Isthmus, which cut off the Pacific Ocean from the cold northern waters. Streams and rivers flowing down from the Beringian Mountains lowered the salinity of the waters of the northern coast of the Pacific Ocean, while enriching them with oxygen. The decrease of salinity is noticeable only near the river mouths, almost without any affecting the richness of coastal fauna and flora. This area is characterized by extensive thickets of brown macroalgae providing food and shelter for many animals. And the abundance of prey caused the appearance of numerous predators. The snake-like wolffish is one of these species.
Snake-like wolffish is a descendant of the wolf eel (Anarrhichthys ocellatus) of the Holocene epoch, but it is an even larger fish: the old individual can reach 3.5-4 m in length. Its body is cylindrical, laterally compressed in the back part, with strongly reduced pectoral fins and absent pelvic fins; tail fin, on the contrary, is well developed, merged with the dorsal one and has a paddle-like shape. This fish swims poorly in the water column and prefers not to leave the algae thickets. A strong body allows it to make fast and powerful rushes from ambush, as well as stick its head into shelters, chasing invertebrates and small fish. The skin of this fish is naked and slimy. The general color is brown with a reddish “marble” pattern of irregular vertical stripes and small black spots on the head and along the base of the dorsal fin.
The head of the snake-like wolffish is large and muscular, with strong shortened jaws and teeth that cause severe damage to its prey – crabs, cephalopods, and other fishes. Thick lips are covered with numerous corneous spikes that allow it to hold slippery prey tenaciously. Due to the cutting edges of the teeth, snake-like wolffish is able to bite through animals with strong bones or shells. Only few animals are able to hunt it – only some seabirds and mammals attack this fish if it turns out to be in the littoral zone. From their attacks, young fishes die most often. The adult snake-like wolffish is one of the main underwater predators of the local ecosystem.
The courtship season of the snake-like wolffish begins at the end of winter. Then males become much more territorial and aggressive, and attract females to themselves with special sounds, uttering series of clicks with their teeth. Females swim to them, explore their possessions and, having found a suitable mate, stay at the male’s territory for several weeks, after which they spawn eggs and swim away. Spawning takes place in a shelter; at the time of spawning, the mates wrap around each other. The clutch of this species numbers up to 50 thousand eggs. The male wraps its body around the clutch and protects the eggs until the fry hatch and until they swim away. This species grows very slowly: sexual maturity comes when it reaches at least 2 m in length, at the age of about 10 years (females mature a little bit earlier).
Most snake-like wolffishes die at an early age, not only from predators, but also from winter cold, as well as from storms that cast them ashore along with algae. But if they manage to survive the first 5-7 years of life, they can expect to live for several decades – the maximum age of this species reaches 70-80 years.

This fish species was discovered by Bhut, the forum member.

Great fibata (Fibata robusta)
Order: Percoid fishes (Perciformes)
Family: Snakeheads (Channidae)
Habitat: Madagascar, seasonal rivers, lakes and swamps in the western part of the island.
In the human era, the fauna of Madagascar largely suffered from human activity. It affected not only terrestrial fauna, but also freshwater one – the introducing of numerous species of exotic fish destroyed vunerable local ecosystems. As a result, by the beginning of Neocene, only a few descendants of local species known in the human era remained in the ichthyofauna of the island, and the vast majority of species living in the rivers and lakes of the island are descendants of introduced species or recent natural settlers from the sea.
In the Neocene epoch, the dominant predatory fishes of Madagascar are representatives of the snakehead family. They do not reach the frightening size of their Asian relatives, but they still confidently occupy the top of the food pyramid in freshwater ecosystems. The ancestor of these species is the blotched snakehead (Channa maculata). Its descendants were helped to survive by the ability to breathe air and the absence of food specialization. These features were embodied by great fibata, a large snakehead species that thrives in the arid areas of the western part of the island. “Fibata” is the local name of the ancestral species.
When rivers dry up, turning into a chain of non-flowing puddles with musty water, the great fibata feels great. It is a predatory fish with an elongated body and a large broad head. The body length of an adult can reach 2 meters, and the weight is up to 50 kg. The body of this fish is colored brown with two longitudinal stripes of sandy yellow. The edges of the stripes are blurred and merge with numerous sand-colored specks scattered on the sides and back of the fish. Unlike the ancestors, the front edge of dorsal fin of the fibata is shifted to the middle of its back; it contains 9-10 strong spikes that protect young fishes from fish-eating birds. The head of this fish is wedge-shaped in profile; the body gradually expands posteriorly, reaching its maximum depth at a distance of about 2/3 of the total length from the tip of the snout. Towards the tail stalk, the body narrows strongly. The tail stalk is deep and strong; it ends with a wide fan-shaped tail fin. The fins are colored brown with transparent edges.
Due to the well-developed suprabranchial organ, fibata is able to breathe air, so this fish easily survives in swamp water and is able to survive drought in contaminated water that almost lacks any dissolved oxygen. About once every half an hour, the fish rises to the surface and breathes for a while, after which it sinks back into the depth.
This fish species is able to eat any animals that fit the size of its mouth. Fishes, including its smaller congeners, waterfowl and their chicks, rodents, frogs and turtles fall prey of the great fibata. Sometimes this fish lurks near watering places and drags small land animals and their cubs into the water.
At the very beginning of the rainy season, when the water becomes richer in oxygen and the growth of aquatic vegetation begins, great fibata spawns. In a male ready for reproduction, the body color turns black with two “marble” white stripes. Golden eyes and thick white lips stand out vividly against the black background of its head. The female turns pale during spawning. The male swims around the female, pinching her sides with his lips from time to time. He also jumps out of the water and flops sideways, indicating his rights to the territory. Among the thickets of aquatic plants, a breeding couple of fish builds a nest – a round construction about one and a half meters in diameter from plant debris and foam, in which up to 70 thousand floating eggs are spawned. The male drives away the female and guards the nest for 3 weeks by himself. The incubation of the eggs lasts 4 days; the fry begin to swim in the 5th day of life. At this time, the male rushes at any animals that appear near the nest.
In the first year of life, the young fish reaches a length of about 8 cm. The juvenile coloration is very different from the adult and resembles the ancestral one – small brown spots scattered over the silvery body and fins. At the age of 4 years, with a length of 1 meter, great fibata becomes sexually mature and finally changes coloration to the pattern characteristic of an adult. Life expectancy can reach 40 years or more.

Amalona (Dolichochanna amalona)
Order: Percoid fishes (Perciformes)
Family: Snakeheads (Channidae)
Habitat: Madagascar, rivers of the western part of the island.
The native ichthyofauna of Madagascar proved unable to resist the flow of alien species introduced to the island during the human era. Insufficient conservation efforts led to the spread of alien species and the mass extinction of native species at the end of the human era. The few surviving species inhabited the river estuaries or lived in extreme conditions that the settlers could not master. In the Neocene ichthyofauna of Madagascar, most species are descendants of fishes introduced in the historical era. In due course of evolution, they have formed new species that occupy their place in the ecosystems of the island.
A characteristic inhabitant of the rivers in the western part of the island is amalona, a large eel-like snakehead reaching a length of about one and a half meters. “Amalona” is the name of the giant mottled eel (Anguilla marmorata) in Betsimisara, one of the Madagascar languages. And it is quite suitable for the descendant of the blotched snakehead (Channa maculata): the body of the amalona is very slender and thin, tapering smoothly to the tail. The fish has a flat head with a terminal mouth; its lower jaw is slightly longer than the upper one. The spiny part of the dorsal fin consists of 18-20 short spines with a reduced fin membrane between them; the spines contain a highly irritating, but generally not too dangerous poison. A prick of such spines causes severe swelling of the tissues, and the aggressor feels weak for several days. The soft part of the dorsal fin, tail and anal fins fuse into a single structure bordering the body. Pectoral fins are well developed; the pelvic fins are short. Eyes are small, turned to the sides and partly upwards.
The coloration of the upper side of the body is variable; depending on the color of the surrounding soil and the abundance of vegetation, it can vary from yellowish-beige with a brown “marble” pattern to dark green with black spots. The lower part of the body, throat and belly of this fish are grayish-white; fins are translucent. There are numerous dark spots at the base of the dorsal fin. Male and female do not differ in color; female is larger than male, and her head is relatively small.
Amalona leads an inactive lifestyle and usually buries itself in the ground, waiting for prey. At this time, only the head and part of the trunk stay outside. The fish feeds on crustaceans, insect nymphs and small fishes, instantly sucking them in with its slightly elongated jaws. When predators appear, this fish tends to dig into the ground. Captured by a predator, amalona wriggles violently and strikes with spines.
Amalona inhabits deep reservoirs that do not dry up during the drought season. In the riverbed, fishes survive the drought in deep pools. At this time, it often rises to the water surface and inhales air. In oxygen-rich water, the fish is content with oxygen entering the body through the gills and skin, and breathes air mainly after hunting, when there is no need to hide at the bottom.
Spawning in this species occurs at the beginning of the rainseason. Fishes build a temporary nest of long-stemmed plants – a flat construction of round shape. At night, the fishes begin a bizarre courtship dance, wriggling violently at the surface of the water. After courtship, the female spawns eggs into the nest – up to 2000 small eggs in total. After the male fertilizes the eggs, both fishes gather them in their mouths and swim away to their shelters. Each individual incubates its portion of eggs alone.
Incubation lasts up to 5 days. Thin worm-like fry leave the parent’s mouth after another 3-4 days, and try to leave the parent territory immediately. After that, the fish actively eats off and after about a week takes part in courtship games again. During the wet season, amalona spawns up to 3 times, while each subsequent portion of eggs is smaller than the previous one. Juvenile coloration represents a double longitudinal dark stripe on a light gray background. Young fishes hide in the thickets of underwater plants, often wrapping their bodies around the stem, and feed on fish fry and planktonic crustaceans.
Sexual maturity in young fishes comes at the age of 3 years; life expectancy is up to 20 years.

Square Bellied Climbing Gourami (Neoanabas amphibius)
Order: Percoid fishes (Perciformes)
Family: Climbing Gouramis (Anabantidae)
Habitat: Lake shallows and margins of Carpentary lake, surrounding marshes and swamp-forest.
Invasive species may reach new shores in many ways, and some simply stow away in the hulls of boats or by slipping aboard their underside. This is how it is theorized that the Climbing Gourami (Anabas) came to Papua New Guinea from Indonesia. This fish eventually proved successful in the Neocene, and has produced one unusual Meganesian form, Square Bellied Climbing Gourami.
These fish a short and blocky in shape, with a large thick-boned head and sub terminal mouth, reaching a total of 30 centimeters long. Fins are broad and rounded, resembling its ancestor, dorsal and anal fins are shallow and run the length of the body, pectoral fins are somewhat enlarged, dorsal fin bears large spines. Colour of the body is a dirty olive green with black speckling, slightly reflective, with light brown fins. The cross section of the fore-body resembles a triangle, with a flat, sledge-like belly; the gill plates are large and expanded towards the bottom, bearing a bony spike. These fish have a labyrinth organ which allows them to breathe air, and they frequently gulp air at the surface. Some sexual dimorphism is expressed, females are larger and thicker.
This fish prefers vegetated shallows, but will frequently cross from one body of water to another. It is a predator, feeding on small fish, crustaceans, insects and worms, caught underwater, on the waters surface, and sometimes on land. Teeth are small but jaws are fairly powerful. This fish is well able to survive protracted periods on land and can live out of water for up to 8 hours so long as the gills remain wet. Unlike its ancestor it will voluntarily leave the water on excursions, wriggling in water of only a few centimetres deep, and venturing some distances onto land in order to hunt insects and other invertebrates. The shape of the gill covers, and the flat belly, allows this animal to move comfortably and relatively well on land, crawling by wriggling to one side and then the other, gaining traction with its spiny gill covers. This fish can tolerate some levels of brackish water and is also found in the swamps surrounding the lake, which may be brackish in their northern reaches. This fish is mostly diurnal, sheltering in thickets of water plants at night.
These fish are not generally social, and ignore each other outside breeding season which occurs from December to March. During the wet season, males develop a reddish colour to their body when ready to breed, and fins also darken. They form temporary pairs, where the male will wrap around the female in order to fertilize the eggs, about 2 hundred at a time until about 5000 are eventually laid after numerous attempts. There is no parental care, the parents scatter the eggs then abandon them, which initially float but sink soon afterwards into the sediment, and are not adhesive. Young become sexually mature at just under a year old. Predators include various large fish, crocodiles, snakes, predatory birds and occasionally carnivorous marsupials. Lifespan is 5 to 9 years.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Sandy spiny eel (Psammomastacembelus echidnops)
Order: Spiny eels (Synbranchiformes)
Family: Spiny eels (Mastacembelidae)
Habitat: Tanganyika passage, sandy shallows in river estuaries.
Mouths of rivers are a fine place for hunting. Here on sandy shallows there is a set of edible live beings – small fishes coming from the sea, inhabitants of the river and dead bodies of ground animals, carrying away by river. One of most favorable strategies of life in such conditions is to rise a head against current and to wait patiently. Usually expectation is renumerated rather quickly: current frequently takes out in sea fry, larvae of insects and small animals had fallen in water.
If to look narrowly at the surface of sand of river shallows where fresh river water meets with salt sea one, in some places it is possible to see how sand moves. In it the superficial, quickly smoothing down groove meanders: under sand certain oblong flexible body creeps. From time to time on surface of sand in cloud of dregs the head of the sand inhabitant appears. This creature is a coiled fish about half meter long with top jaw sticking forward and tiny eyes – the sandy spiny eel.
Spiny eels are characteristic fishes of Africa and Southern Asia. They are similar to eels, but spikes on back are the rest of prickly back fin, characteristic for percoid fishes. After Great Split of Africa and separating of the Zinj Land from it these fishes, especially numerous in Great African Lakes, partly had died out, and partly had survived, having receded in the rivers. Some species, able to endure salt water, had mastered life in lower reaches of rivers. The sandy spiny eel is one of such species.
Similarly to many representatives of family, this species is digging fish as if “swimming” in thickness of sand, digging burrows with the help of firm top jaw extended forward. In thickness of sand the most part of life of this fish takes place, and it has dint on its appearance: eyes of sandy spiny eel are tiny, “weak-sighted”, with very thick cornea. Fish is very short-sighted, but as indemnification for bad sight at it the sense of smell is excellently advanced. The sandy spiny eel frequently sits in ambush, having dug in sand so, that only eyes and nostrils jut outside. This fish is bad swimmer for long distances: all fins of it are very short. But the body of this species is powerful and muscled, band-shaped in back part – with the help of wide tail this spiny eel easily digs for itself road in sand and in case of danger instantly can dig in it. Colouring of its body simulates the color of environment: creamy-white body with “marble” beige pattern and separate black and brown speckles.
Sandy spiny eel is a predator. It hunts small fishes and shrimps from an ambush in sand, catching them by sharp throw. Trapping catch, fish is dug in the uppermost layer of sand and exposes outside only a head. Sharp sense of smell prompts the fish when in immediate proximity from it crab or shrimp runs on sand. Then sharp throw instantly follows, and catch convulsively beats in jaws of fish. Having crumpled with crunch its catch by jaws, the spiny eel swallows it entirely, and continues the waiting in sand. It is not frightened even with outflow: this fish easily sustains recession of water, and perfectly feels in moist silt sand in succession of many hours. If the sun has dried the top layer of sand, this spiny eel simply digs in moist layers in depth, waiting for inflow.
But being well adapted to life in estuaries of rivers and at the coast of Tanganyika passage This fish species nevertheless is the descendant of freshwater fishes. And it has had an effect in features of biology of sandy spiny eel - it spawns in river headstreams. At night, with the highest inflow, these fishes leave sand and with a tidal wave swim to river mouths. In outflow they dig in river bottom and some time get accustomed to fresh water where they should execute the duty to the future generations. In colouring of fishes there are remarkable changes: from “sandy” it becomes striped and contrast - on light background green vertical strips appear, on tail forming irregular pattern. Gradually fishes start to gather in schools and to move upstream, choosing for this purpose night and richest thickets of plants along riverbanks. For some nights they reach river upstreams (rivers of the East-African subcontinent are short) where in thickets of marsh plants spawning takes place. Males rise in rivers more unanimously and faster: it is connected with features of their courtship behavior. Usually one female spawns with two - three males. Fishes rise to surface of water, wriggling and even plaiting together. They get into thicket of long-stem plants (water moss, bladderwort, or others small-leaved plants) in shallow water, and spread eggs on them. After spawning females quickly leave the rivers and swim down to the sea and males remain to expect new females.
In 3 days from eggs transparent larvae hatch. About two weeks they hide among plants, and then start to leave plants and to search for food in silt. Approximately to half-year age (at length about 20 cm) they begin movement from river upstream to river mouth. At two-year-old age ones will have the luck to survive, will return to the river for spawning.

Glass spiny eel (Benthomastacembelus semicaecus)
Order: Spiny eels (Synbranchiformes)
Family: Spiny eels (Mastacembelidae)
Habitat: rivers of equatorial Africa, bottom silt at depth.
Spiny eels are characteristic tropical bottom-dwelling fishes of the Old World, common in Africa, South Asia and Zinj Land. In the human era, the number of large species decreased significantly due to habitat destruction, but small species managed to keep viable populations and survive the era of the global ecological crisis. In the Neocene epoch, representatives of the family lead a lifestyle characteristic of their ancestors in the historical era, without encountering serious competition from other groups of fishes. Some Neocene species display a deep specialization to the burrowing lifestyle.
One of the most unusual species of the group – glass spiny eel – lives in the rivers of the Atlantic Ocean basin. It has a specific habitat – a layer of soil at the bottom of large rivers. This inhabitant of the dark depths retains juvenile features in its appearance – it is translucent, and its eyes are greatly reduced and are only able to distinguish light from darkness and perceive the appearance of large objects in the field of view. The body of this species is ribbon-shaped and translucent: through the skin and musculature, the insides are visible and even the beating of the heart is noticeable. There is a faint “marble” pattern on the skin: a chain of grayish spots along the side and specks on the back. The body length of an adult is about 20 cm.
9-12 small reduced spines grow in the dorsal fin; the unpaired fins are reduced to low leathery ridges; the pectoral fins have completely disappeared. The snout is very much elongated; its mouth is tubular, capable of sucking any small prey in. The lack of vision is compensated by an acute sense of smell and well-developed lateral line organs. Also, this species has electroreception, although it is unable to produce a strong electric field like true electric fishes.
This fish species swims very rarely and leaves the ground only in case of extreme danger. Usually, glass spiny eel almost constantly keeps in a layer of soft bottom silt, sticking out only its head and the front part of the body. When attacked, the fish rapidly buries itself in the ground, and only if it is impossible to do this, it swims away, rushing in zigzags. The fish captured by the enemy produces a large amount of slime and escapes, slipping out of the capture.
Glass spiny eel feeds on insect larvae and oligochaetes, as well as small fishes, snatching them from ambush.
Spawning occurs at night in shallow water in coastal vegetation. Ready-to-breed fishes gather in schools of 5-10 individuals with approximately equal numbers of males and females, and hide deep in the thickets of small-leaved plants, scattering their eggs on the leaves. The fertility of the female is up to 20 thousand eggs. These fishes express no parental care and swim away to the depths by dawn. Spawning is repeated 2-3 times a year. The young hatch after 36 hours and begin to swim after another day. Young fishes are glass-transparent with dark eyes and insides. Sexual maturity comes at the age of 1 year; life expectancy is about 10 years.

Mud-dwelling spiny eel (Paramastacembelus paludicolus)
Order: Spiny eels (Synbranchiformes)
Family: Spiny eels (Mastacembelidae)
Habitat: Zinj Land, temporary reservoirs.
The inhabitants of temporary reservoirs were the winners during the biological crisis at the turn of the Holocene and Neocene. They were initially adapted to rapid development and the use of a small amount of resources available only for a short time. Therefore, in the era of ecological crisis, they gained an advantage over long-cycle and slow-growing species. The usual inhabitants of temporary reservoirs are egg-laying toothcarps (annual killifishes). However, there are fish species from various continents that can live for a long time in temporary reservoirs, and survive drought in shelters, as did Protopterus – African lungfish of the human epoch. One of the species of such fishes is mud-dwelling spiny eel – a representative of a peculiar group of eel-shaped fishes.
This fish species has a very elongated body covered with abundant slime; the length of an adult reaches 55-60 cm with a maximum body depth of about 15 mm. The coloration is pale yellow with small brown speckles on the back and a stripe of large strokes along each side. On the head, there is a brown “mask” covering the eyes and sides of the head. The skin is scaleless and is covered with copiously secreting slime, which facilitates its movement in the ground. When attacked by a predator, the fish secretes a lot of viscous slime, and thus can escape by slipping out of its jaws. The snout is covered with a hard skin that allows this fish to dig tunnels in the ground. The eyes are very small, shifted to the top of the head. Usually the fish lies in the thickness of the ground, exposing the upper part of the head with eyes and back.
Adaptation to life in reservoirs with sun-heated water poor in oxygen was accompanied by the appearance of additional respiration structures. In the mouth of this fish, folds of skin develop, covered with papillary epithelium and penetrated by blood vessels. In drought and with the deterioration of the oxygen regime of the reservoir, the fish survives by taking air bubbles from the surface of the water and extracting oxygen directly from them. In wet seasons, due to additional organs of air respiration, this fish can crawl from one reservoir to another, settling to new habitats.
Like all its relatives, this species is a predator. The prey of mud-dwelling spiny eel consists of annual fishes, ephemeral crustaceans (tadpole shrimps, branchipods) and other short-living inhabitants of temporary reservoirs. Usually the hunting fish lies on the surface of the ground, slightly buried in it and S-bending its body. When prey appears, the fish sharply straightens its body and catches it, remaining buried in the ground with the posterior part of the body.
The mastering of temporary reservoirs by this species was facilitated by the burrowing lifestyle of spiny eels. It took quite a few changes in behavior to transform the temporary tunnels in the ground into a reliable shelter that allows the fish to survive during several months of drought. Mud-dwelling spiny eel survives drought by burying itself deep into the soil and surrounding itself with a slime capsule. Its slime glues the soil particles into a sufficiently dense cocoon, which protects this fish against moisture loss. Sleeping during the drought, the fish breathes with the help of the epithelium of the mouth cavity, as well as its skin.
Spawning takes place at the very beginning of the rainy season, in the thickness of the silt layer. Fishes spawn in a group where the number of males and females is approximately equal or males predominate. Fishes curl into a tight ball, spawning eggs into the ground and not caring about it anymore. The young fish feeds on small aquatic animals and grows rapidly, reaching a length of about 10-15 cm by the end of the dry season. A significant number of young individuals die in the first drought. Sexual maturity comes in the third year of life; life expectancy does not exceed 15 years.

“Evil sun” flounder (Actinobothus sol-malevolus)
Order: Flatfishes (Pleuronectiformes)
Family: Lefteye flounders (Bothidae)
Habitat: northern Pacific Ocean, depths up to 2-3 km, ocean floor.
In the Neocene epoch, the species composition of deep-sea fish fauna changed radically due to the “plankton catastrophe”. Some of the deep-sea fish species passed the early stages of development as part of the plankton, and all, without exception, the species depended on the “rain corpses” from the upper layers of water, which ensured the flow of organic matter into the depths of the ocean. Therefore, deep-sea fishes of the Neocene are descendants of shallow-water forms that have mastered the depths of the oceans. Among them, various flatfishes, that “moved down” to the depths along the continental slopes and mastered even the ocean abyssal zone, are characteristic
One of the numerous species of deep-sea flounders is a flounder species from the depths of the Pacific Ocean, named as “evil sun”. The appearance of this species is very characteristic: the body is about 20-25 cm long, expanded and is of almost discoid shape with shortened tail stalk. The fin rays are greatly elongated: they reach a length of 30 cm, protrude from the fin membrane and surround the rounded body of the fish from almost all sides, forming a semblance of a stylized image of the sun. The pelvic fins are reduced to two rays connected by a membrane. The pectoral fin on the blind side is absent; on the upper side it is well developed and helps to move over short distances. The scales of this fish are reduced and immersed in the thickness of its skin. The pigmentation of the skin is well developed: the upper side is coal-black; the lower side is white and depigmented. The insides are seen through the skin on the lower/blind side of the body, and the soft bones of the fins are visible along the edges of the body. On the upper side of the body, there are numerous small photophores that the fish can light and extinguish at will.
The head is short, with a sloping mouth, which can open very wide and is equipped with numerous thin teeth. Due to the stretchable ligaments between the flexible jaw bones, the fish is able to swallow prey the size of itself. The eyes are located on the upper (left from the anatomical point of view) side of the body and are greatly reduced: they are barely able to distinguish light from dark.
Waiting for prey, the “evil sun” flounder lies on the surface of the silt. Due to the elongated fin rays, it does not sink into fine-grained sediment. Luring its prey, the fish randomly lights and extinguishes its photophores, mimicking the chaotic movement of a certain small creature. The “evil sun” flounder feeds on crustaceans and fish.
There is no seasonality in reproduction. The male is about twice as small as the female. Fertility is up to 50 thousand small eggs; spawning is repeated up to 5 times a year. Eggs are pelagic, with a large fat drop; being spawned, they float up and develop in the upper layers of water. The larvae have well-developed eyes; they are planktonic predators. Already at the planktonic stage, this species has strongly elongated rays of unpaired fins that facilitate hovering in the water column. With a length of about 40 mm, the transparent larva begins to descend into the depths of the ocean and undergo metamorphosis. Sexual maturity comes at the age of 3-4 years. Life expectancy reaches 50 years or more.

Arafura Wolf-flounder (Compressolycus lacustris)
Order: Flatfish (Pleuronectiformes)
Family: Sand Flounder (Paralichthyiidae)
Habitat: Arafura Lake in Northern Meganesia, bottoms from shallows to a depth of about 30 meters, will also swim in water column.
The closure of Arafura Sea and Carpentaria Gulfs, into large brackish lakes, afforded opportunities for some sea fish to specialize towards new niches and habitats. Flounder were one of them, being relatively tolerant of salinity changes, and indeed some Holocene flounder became adapted to brackish and even fresh water.
Thus, from typical predatory flounder of the genus Pseudorhombus, Arafura Lake plays host to the Wolf Flounder. This fish reaches 1.7 meters long, and though still flat in shape, is adapted to not only feed by ambush, but as with the halibut, to chase prey some distance. Accordingly, dorsal, anal and caudal fins have a more active, semi-triangular shape. The jaw is long and projecting, bearing some similarity to a small halibut, but with proportionately longer teeth. Eyes are left-sided, and ability to change colour is somewhat less that with its ancestor, it can change tone and lightness/darkness but not make a great deal of patterns.
This fish is found mostly near the lake floor, but not at greater depths, where settling salt reaches less tolerable levels. It can travel in various layers of the lake when it has to, being tolerant of salinity changes, including those of changing tides. Arafura Wolf Flounder is active mainly during the afternoon and evening, and its eyes are large, bulging, it hides on the lakebed in shallower areas by day.
Spawning takes place during the wet season, both males and females migrate into mangrove swamps to spawn, eggs and larvae mature in shallow ocean water and near shore lagoons. The young are initially free floating but come to resemble miniature adults at an age of 6 months, after which they undertake migration back to the lake. Males reach sexual maturity at 10 months; females are able to lay eggs at a year old.

This fish species was discovered by Timothy Donald Morris, Adelaida, Australia.

Antarctic amphibious flounder (Batrachopsetta amphibia)
Order: Flatfishes (Pleuronectiformes)
Family: Armless flounders (Achiropsettidae)
Habitat: littoral zone of Antarctica.
In the Neocene, Antarctica, being isolated from other continents and partially freed from ice, became a kind of laboratory of evolution. Among the Antarctic land inhabitants, there are huge land-dwelling shrimp, insect larvae replacing earthworms, and birds mimicking rodents. Peculiar creatures have also appeared among the coastal marine fish of Antarctica.
The Antarctic amphibious flounder is a marine fish that lives in the littoral zone of Antarctica and has partially passed to terrestrial life. The body of this fish is deep and strongly compressed from the sides, oval in shape. Like related species, this fish lies and swims on its side. Its eyes are also located not on both sides of the head, but shifted to one side of it, like all flounders, but unlike them, the eyes of amphibious flounder are similar to frog’s eyes – they protrude strongly above the surface of the body and are mobile. There is no swim bladder, like all flounders. The upper side is pigmented, and the fish can change color pattern; the lower side is white. The usual coloration is brown with green spots and numerous black dots, but it can vary widely, up to almost monotonous black and sandy yellow.
Staying under water, this fish breathes with the help of gills, but it also has skin respiration, due to which it is able to stay on land for several hours. The fish has a short “cut” caudal fin with hard fin rays, the tips of which protrude from a thick membrane. It is a device for pushing against the ground, so that the fish can make short jumps forward when chasing its prey and move in shallow littoral pools during low tide. Anal and dorsal fins help it in underwater moving with their undulating movements. At low tide, the fish buries itself into the sand or silt, and comes out of its shelter only with the beginning of the tide.
Antarctic amphibious flounder is carnivorous; it feeds on fish and benthic invertebrates – crustaceans, mollusks, worms, etc. During low tide, this fish can hunt small birds searching for food in the littoral zone.
Spawning takes place in spring, when the water temperature rises. Fertility is up to 500 thousand small pelagic eggs. The incubation period is up to 3 days. Flounder larvae initially float in the water column, but as they transition to a benthic lifestyle, the body becomes deeper, the fish begins to swim on its side, and the eyes move to one side of the body that becomes the functionally upper one. Fishes become sexually mature at the age of 3-4 years. The maximum size is up to 40-50 cm with a weight of up to 3 kg. Life expectancy is up to 45-50 years.

The description of this species was compiled by Wovoka, the forum member.

Angler sole (Lophiosolea piscatorius)
Order: Flatfishes (Pleuronectiformes)
Family: Soles (Soleidae)
Habitat: Tanganyika passage, mangrove thickets and sandy shallows; also it can come in river mouths and to live some time in fresh water.

During ecological crisis at the boundary of Holocene and Neocene among sea fishes such species had survived, which had an opportunity to exist in ecosystems, less suffered from accident – in benthos and rivers. Therefore there was the chance of survival at plenty of shallow flatfish species. Though fishes of this group spawn in sea water, and the larva spends first days of life in plankton, they quickly pass this stage and early begin able to live even in completely fresh water. In rivers there are different flounder species, in tropics among them there are soles (Soleidae) to which the angler sole belongs.
This species had kept the body shape typical for family: short rounded head and sharp tail. Usually these fishes are right-hand, though about 15 - 20 per cents of population are “lefthanders”. The length of body of this fish is rather small – about 20 cm. Mouth is skew, eyes are located this kind: one is near a corner of mouth, another one is near tip of muzzle. Eyes are large, raised above body surface on small eminences. They stick up from sand when the fish is dug in it, trapping catch. Colouring of the eyed side of body can vary over wide range: from dark-grey up to yellowish and almost white, with spots or without spots depending on color of bottom. Usual colouring of fish in rest is yellowish-grey with randomly scattered black spots. The male is smaller than female, at him there are more oblong body and large head.
As against to related species passively expecting when catch itself will come nearer to the distance of exact throw, this sole can allure catch, for what at it the original adaptation is developed. On pectoral fin of the painted side of body the first ray is not attached to others. It can move independently of others due to several muscles in its basis. On the end of this fin ray there is a rag of fin membrane, alluring small fishes. The pectoral fin is shifted forward to middle of branchial cover. On the eyeless side of body skin is light pink or white, the pectoral fin is strongly reduced: from it some fin rays are kept. Tail fin has partly grown together with back and anal ones.
The angler sole prefers to keep on sandy shallows in rivers estuaries and at coasts of passage. It easily maintains desalination of water and even comes into lower reaches of rivers. But for spawning these soles leave shallows in river estuaries and swim to coast of passage where water has normal salinity. The male begins courtship for the female, actively chasing her; it is not a rarity when at once two males chase for the female. Male snaps front edge of anal fin of female, and does not release it for some time, being dragged behind the female on the bottom. When the female lies down on bottom, the male releases her fin and “stands” above her, driving other males away and even rushing to fishes of other species.
For egg spawning pair of fishes for a short time leaves bottom, quickly emerges almost to the surface of water, simultaneously “throws” eggs and soft roe and as promptly falls on a bottom and buries in sand. Their care of posterity comes to an end at this moment.
Larvae leave egg shells in two days, in one week they turn to translucent asymmetrical fry and pass to life of adult individuals. First time fry eats small crustaceans and worms. At four-monthly age they reach length of 7 - 8 cm and then at them the bait of “fishing tackle” starts to form.
Sexual maturity comes at the age of 8 - 10 months at body length about 15 cm. Life expectancy is no more than 5 years.

Large-headed sole (Cryptosolea macroceps)
Order: Flatfishes (Pleuronectiformes)
Family: Soles (Soleidae)
Habitat: Atlantic Ocean, thickets of algae to the south of New Azora island.
In Neocene circulation of ocean currents has undergone some changes: in Atlantic two circulations of water masses have appeared. One of them is located in southern part of ocean, and the second one is in the top water layers to the south-west from New Azora island - top of the Middle-Atlantic ridge. Here the water from depth sated with phosphates and nitrates rises to surface of ocean along slopes of mountain ridge. It causes plentiful growth of bushy brown algae similar to Sargassum algae of Holocene epoch. Floating algae is a fine habitat for set of species of fishes. Basically, descendants of coastal species whose fry and larvae were brought here by currents, live here. Among them even the special species of the flounder has lost connection with bottom habitats have appeared.
Large-headed sole is this flounder living among seaweed. At it there is a wide body with acute tail. Tail fin as such is not present, back and anal fins grow together on the pointed back end of body: it is a common attribute of family. Certainly, it is not the attribute of good swimmer, but this flatfish species, as well as the majority of inhabitants of algal “fields”, does not like to swim long and quickly. Length of large-headed sole is up to 25 cm.
On unpaired fins (back and anal) some forward beams are transformed to finger-shaped outgrowths with which help the fish keeps in plant thickets. Large-headed sole swims badly, but dexterously moves among plants, using these increased fin rays. Tips of fin rays have turned even to a semblance of claws, helping this fish to cling to seaweed. The fish spends a significant part of time, having strongly grasped by “fingers” for thalli of seaweed. Art of masking allows to large-headed sole to exist in such conditions extraneous to flounders at first sight. The fish is a predator, and traps catch (crustaceans and small fishes), masking among seaweed. Eyeless and eye-having sides at This fish species are colored equally (it makes large-headed sole the exception among flounders) reddish-brown with orange-yellow and dark-brown spots imitating light and shadow among seaweed. In case of necessity the fish easily changes color from light yellow up to almost black. Such masking permits fish to expect possible catch, not involving undesirable attention.
The head of fish is rather large, the most part of it a sliding mouth extending to long tube accounts. When catch of suitable size appears close, the fish by lightning movement extends mouth, and sucks in it the prey. Eyes of this fish are large, located on one side of body. They strongly stick up above the surface of body, and are similar to eyes of frog. Due to such eyes this flounder has the good circular field of view. Almost identical amount of right- and left-sided fishes in population is typical for large-headed sole.
These fishes breed similarly to all flounders: they spawn in water and not care of posterity. Male is smaller than female, but during courtship ritual it behaves more actively than female: male chases her, nestling to her by eyeless side. The male always chooses the female by its own similarity: it prefers female at which eyes are on the same side of body. In spawning season the male becomes brighter, and he shows to female bright colouring of the eyeless side of body, “hovering” above the female. For one breeding season (in warm season, since April till October) the female of this species can spawn eggs up to six-seven times, and single fertility makes about five thousand small eggs.

Ribbon sole (Taeniosolea muraenosoma)
Order: Flatfishes (Pleuronectiformes)
Family: Soles (Soleidae)
Habitat: coastal waters of Antarctica and Subantarctic region.
Flatfishes are one of the most unusual groups of teleost fish. Having evolved in the Eocene, they managed to survive the ecological and geological catastrophes that accompanied the change of epochs due to a specialized benthic lifestyle. The transition from Holocene to Neocene also did not become a disaster for flatfishes: in the new conditions, these fishes managed to increase their number and species diversity. They managed even to make several attempts to develop ecological niches new to them, passing from the benthic to the pelagic lifestyle. Some flatfish species have become formidable sea hunters – for example, wolfhalibut (Serrassalmoglossa lupina) from the cold waters of the Southern Hemisphere. Its relative and neighbor, the ribbon sole, also belongs to the number of predators.
Ribbon sole occupies an ecological niche of moray eels off the coast of Antarctica and nearby islands. It hunts small and medium-sized fish, as well as cephalopods and occasionally small seabirds. The hunting tactics of this fish is simple: it waits for the appearance of prey, hiding in the crevices of coastal rocks. When the potential food is close, the ribbon sole catches it, leaning out of its shelter, and devours it.
The appearance of the ribbon sole is somewhat similar to that of typical representatives of the order, but has features of specialization to an unusual lifestyle. The body of this fish, like that of all flatfishes, is laterally flattened and asymmetrical, but the fish usually keeps it in a vertical rather than horizontal plane. The body of the fish is very elongated and resembles a ribbon in its shape; the length of the ribbon sole can reach 1.2 meters with a weight of up to 8 kg. Both eyes are located on the right side of the body and are strongly shifted forward – so it is more convenient to watch for prey. Dorsal, anal and caudal fin have fused into a single border around the posterior end of the body. The color of this fish is usually grayish-brown with dark spots, but it can easily change depending on the prevailing color of the environment. Since the ribbon sole never lies on its side, as its ancestors did, the color of its blind side almost does not differ from the color of the eyed one.
This fish spends almost all its life in the crevices of rocks. If she does have to leave its shelter, it experiences stress and tries to stay at the bottom. The ribbon sole does not belong to good swimmers and swims very uncertainly. However, during the courtship season, these flounders change their previous habits, leave their possessions and gather in groups to breed. Spawning takes place in the upper layers of water and in shallow water. Males attract females with their unpaired fins turning white for the breeding season. While courting the females, the males bite them slightly while swimming next to them. One female may be chased by two males at once, but groups of several males and females often gather, synchronously performing the courtship ritual.
These fishes are pelagophiles. Very small eggs with a small fat drop are spawned into the water in astronomical numbers (the fertility of the female can reach a million eggs), and parents do not care about it in any way. The larva of the ribbon sole is planktonic. Young fishes grow relatively slowly: they spend up to six months in plankton, and only in the fourth year of life they get the opportunity to reproduce. The life expectancy of ribbon soles can reach 25-30 years: individuals who have escaped diseases and enemies – large seabirds and predatory fishes – reach this age.

This fish species was discovered by Simon, the forum member.

Glass skew-mouth (Pelagosolea pellucida)
Order: Flatfishes (Pleuronectiformes)
Family: Plankton flatfishes (Planktosoleidae)
Habitat: temperate waters of the southern hemisphere, open ocean.
The “plankton catastrophe” at the turn of Holocene and Neocene led to a significant renewal of the species composition of plankton and necton of the open ocean. Many groups of pelagic animals known in the human era have become extinct. But in Neocene, when favorable conditions were restored, new groups of planktonic organisms appeared, and some of them represent amazing evolutionary experiments. One of the characteristic groups of planktonic organisms is plankton flatfish family, in which the pelagic stage of development was delayed during their evolution and the benthic adult stage was completely lost.
Plankton flatfishes represent a group closely related to vertical flatfishes. Representatives of both groups are deep-bodied and spend the first stages of ontogenesis in plankton, but then angelfish flounders migrate to rivers (in Antarctica – only for the summer), and plankton flatfishes spend their whole lives in plankton and do not enter fresh waters, although they do not avoid areas of the seashore where water has lower salinity due to flowing rivers.
Plankton flatfishes have almost completely transparent shortened bodies (internal organs are shielded by a silver lining of the peritoneum), “extendable” jaws, a mouth stretching into a tube with numerous needle-like teeth and very elongated rays of the dorsal and anal fins. The skeleton is seen through the skin, and heart beatings are noticeable through the peritoneum.
Glass skew-mouth lives in the upper layer of water – from the surface to a depth of 100-150 meters. It is a fish about 10 cm long; the head makes about 1/4 of the total length of the fish. Its mouth is wide, equipped with numerous bristle-shaped teeth, sloping to the right. The right eye remains on its side and in the process of ontogenesis only slightly shifts downwards. The left eye shifts more, and in adult fish it is located on the midline of the head and faces forward; the left side of the body is blind.
The spines of the dorsal and anal fin are greatly elongated and protrude from the fin membrane – their length is approximately equal to the length of the fish’s body. In the dorsal fin, there are up to 15 such spines, in the anal one – 10-12. At the tips of such spines, there are small rounded flaps of the fin membrane. These spines give the fish the appearance of a sun disk with rays. Due to them, the fish drifts in the water column, spending almost no energy. For fast translational movement, the glass skew-mouth uses its tail fin, and for slow movement it uses the right pelvic fin shifted to the throat (the left one is greatly reduced). The pectoral fins are elongated and pointed.
Glass skew-mouth feeds on soft-bodied invertebrates and fish fry. A significant part of its diet consists of jellyfish and salps with watery soft bodies. Crustaceans become prey of this species very rarely because of their hard covers. The fish sucks its prey in by pulling out its mouth stretching like a pipe. These fishes swim poorly and keep in congestions of planktonic invertebrates.
Spawning occurs in spring and summer. 2-3 times a season, the female spawns about 200 thousand small eggs in the water column, and the male immediately fertilizes them. This species lacks parental care. The fry leads a predatory lifestyle and feeds on planktonic copepods. With age, it switches to eating soft-bodied animals. Sexual maturity comes at the age of 3 years; life expectancy reaches 20 years or more.

Antarctic false angelfish (Verticalopsetta pseudopterophyllum)
Order: Flatfishes (Pleuronectiformes)
Family: Vertical flatfishes (Verticalopsettidae)
Habitat: fresh water bodies of Antarctica.
The mass extinction of oceanic fishes associated with the “plankton catastrophe” at the turn of Holocene and Neocene gave the descendants of coastal and benthic species a real opportunity to pass to a pelagic lifestyle. Among the new inhabitants of the open ocean, there are even such specialized species as flatfishes. Their evolution into pelagic animals has left several small groups on Earth that show different stages of adaptation to pelagic lifestyle. In fact, these are deviated lateral branches of the mainstream line of pelagic flatfishes. They persisted in conditions of reduced competition in some parts of the Earth.
Antarctica, freed from the ice cover, had no its own fish population, and even dragonfly nymphs occupied the ecological niche of fishes there. And from the sea into the Antarctic rivers very peculiar descendants of flatfishes penetrated – vertical flatfishes. The body position in these flatfishes is typical for the vast majority of teleost fishes, but completely atypical for flatfishes: these fishes keep their bodies in vertical position, although numerous features of the body anatomy are characteristic of ordinary “recumbent” flatfishes. Vertical flatfishes separated from other flatfishes by suspending metamorphosis at an early stage, when the fry still retains the vertical position of the body, but the transformation of its skull has already begun. The eyes of these fishes are remarkable in their different sizes, although this difference is not as pronounced as in cyclops soles, to which these fishes are related. These are right-sided flatfishes, and their right eye retains its normal position on the head. The left eye is located on the midline of the body; it is larger than the right one and is directed forward and can turn slightly to the sides. The mouth of this fish is also slightly slanted to the “sighted” side. The gill cover and the base of the pectoral fin on the “blind” side are raised above the midline of the body, and on the “sighted” side, on the contrary, are slightly lowered.
Antarctic false angelfish has a very remarkable appearance. It is a fish about 20 cm long with a body depth of up to 30 cm or more. The outline of its body is diamond-like, and only the tail stalk with a triangular fin breaks these outlines. The head is short, with the mouth slanted up and sideways. The dorsal fin begins just above the upper edge of the left eye and stretches almost to the tail stalk. The anal fin begins slightly before the lowest point of the body and also extends to the base of the tail stalk. Pectoral fins are normally developed, but the fin on the “blind” side shows signs of reduction – the number of fin rays is somewhat reduced; it is narrower and longer than the fin on the “sighted” side.
Only one (right) pelvic fin is present; in rare cases another fin appears, but it is rudimentary, reduced to a short spike. The pelvic fin has long rays; it is elongated and pointed. With its help, the fish can fix itself in the current, holding on to the plant stems.
The body of Antarctic false angelfish is colored beige with dark intermittent vertical strokes. Both blind and sighted sides of this fish have the same coloration. The pectoral fins of this fish are transparent, and the unpaired fins are colored brownish yellow. In males, the end of the pelvic fin is white – it is a feature of sexual dimorphism along with a smaller size and more saturated coloration.
Like its ancestors, Antarctic false angelfish is zoophagous species. With its slanted mouth, it scrapes sedentary animals from the stems of marsh plants, among which it prefers to keep. To feed, the fish turns to the stem with its “sighted” side and orients itself in the search for food with the help of the eye located on it.
This is a migratory fish, like almost all fishes of Antarctica. In autumn, Antarctic false angelfishes migrate singly or in small schools to the sea, where they winter while the rivers of Antarctica are ice-bound and frozen hard. In seawater, their eggs and soft roe form.
Spawning of these fishes takes place exclusively in seawater, where the eggs of these fishes can develop and the first stages of offspring development take place. In the spring, the courtship games begin, which represent a very curious show. Males get a special courtship dress – a “marble” black pattern on a white background. The variability of color is very great: among males there are both almost white individuals with few black spots on the head, and almost entirely black fishes with white spots on the sides and tail. Females at this time get a monotonous gray-blue color. Males court the females by touching their bodies and heads with elongated pelvic fins. At this time, the male chases the chosen female, making “fluttering” movements with his unpaired fins and blocking her path. When the pair has formed, the male gets the same coloration as the female, but the pelvic fin remains black-and-white. At the moment preceding the spawning of eggs, the male grabs the female with his pelvic fin and holds her firmly. An entangled pair of fishes swims near the surface of the water.
Antarctic false angelfishes are pelagophiles. The fertility of the female is about 100 thousand very small eggs with a fat drop. Eggs develop in the upper layers of water, and within 10-12 weeks the fry gradually undergo metamorphosis.
After spawning, adult fishes return to the rivers, where they feed on insect larvae. The juveniles of the first year of life live mainly in the mouths and lower reaches of rivers, but the next year young fishes rise tens of kilometers upstream.
The development of Antarctic false angelfish is very slow. Sexual maturity comes at the age of 4-5 years, but life expectancy reaches 30 years or more.
The vertical flatfish family is common in the waters of the Southern hemisphere. Sea currents have had a great influence on the distribution of these fishes, and the range of the family is very fragmented – the habitats of various species are separated by hundreds of kilometers of open ocean.
Tierra del Fuego harbours a related species – crystal non-angelfish (Verticalopsetta juvenilis). It is a small fish, which is a partially neotenic form closely related to the Antarctic species. It is a much smaller fish – its body length does not exceed 10 cm at a depth of about 15 cm. It is distinguished by a translucent diamond-shaped body with dark vertical stripes and transparent fins. This species feeds on planktonic crustaceans and insect larvae. Crystal non-angelfish inhabits the rivers and swamps of Tierra del Fuego and nearby islands, as well as the far south of South America. It is able to grow and develop in reservoirs of various salinity levels, but spawns its eggs exclusively in seawater. This fish spawns in pairs or in small schools in thickets of brown and green algae.

The idea of the existence of this group of fishes was expressed by Simon, the forum member.

Coin-like cyclopsetta (Cyclopsetta numisma)
Order: Flatfishes (Pleuronectiformes)
Family: Vertical flatfishes (Verticalopsettidae)
Habitat: New Zealand, rivers and brackish lakes.
The ichthyofauna of New Zealand before the human arrival to the archipelago was characterized by its scarcity. All the fishes of the archipelago were diadromous and spent more or less of their life cycle in the sea. During the human era, a number of species of true freshwater fishes introduced from the continents appeared in the fresh waters of the islands. In the late Holocene and early Neocene, the ichthyofauna of the islands became significantly impoverished – without human control settler species superseded most of the local fishes. After the end of the ecological crisis, new fishes appeared in the New Zealand ichthyofauna; among them there were representatives of the vertical flatfish family.
The largest species of vertical flatfishes inhabits Meganesia, and several miniature species of this group live in New Zealand. One of them is coin-like cyclopsetta, a fish about 8 cm long. Its appearance is very characteristic of this group.
The body of coin-like cyclopsetta is strongly laterally compressed and has the outlines of an almost regular circle, broken only by the head and tail of this fish. Head is relatively small, with a wide mouth extending into a short tube. This species belongs to right-sided flatfishes: the right eye is on the side of its head. The left eye is located on the “edge” of the head above the mouth and is directed forward.
Fins are relatively short; the rays in the prickly and soft parts of the unpaired fins are approximately the same length. Tail stalk is short, with a wide trapezoidal fin. The outlines of the fins somewhat smooth out the breaking of the rounded shape of the fish’s body by tail.
The blind (left) side is colored white with a slight silver tint; there are several small black spots scattered on it. The sighted (right) side is silvery, with black spots forming a “marble” pattern. Like all members of its family, this fish swims, keeping its body in vertical plane. Coin-like cyclopsetta lives in the thickets of underwater plants and reeds, where the “marble” pattern helps it hide from enemies. The unpaired fins are transparent. The anterior rays of the pelvic fin are elongated and serve as tactile organs.
This species is carnivorous. Coin-like cyclopsetta feeds on small invertebrates – crustaceans and insect larvae.
Like all flatfishes, coin-like cyclopsetta spawns in seawater. In spring, these fishes migrate downstream in schools and spend several days in the estuary, adapting to the change in salinity. At this time, fishes get a courtship dress: the spots disappear, and the general body color becomes silvery with a bluish tinge. Spawning occurs in schools in the surface layers of seawater. Pelagic eggs are carried away by the current into the sea, and already formed fry return to the shores of New Zealand. After spawning, adult fishes sink to the bottom, get back their mottled coloration and return to the rivers again.
Young fishes become capable of reproduction at the age of one year, and life expectancy does not exceed 8-10 years.

The idea of the existence of this group of fishes was expressed by Simon, the forum member.

Australian rhombida (Rhombida australis)
Order: Flatfishes (Pleuronectiformes)
Family: Vertical flatfishes (Verticalopsettidae)
Habitat: Meganesia, Eyre Gulf.
Representatives of the vertical flatfish family characteristic of the southern hemisphere are widespread mainly in fresh and sea waters of temperate and cold climatic zones. Their species are found in Antarctica, Tierra del Fuego and New Zealand. But some species of these fish managed to settle outside the main range of the family.
The largest species of the vertical flatfish family is found in the Eyre Gulf (southern part of Meganesia), standing apart from other species both in distribution and ecology. This is an Australian rhombida, a thermophilic predatory fish up to 40 cm long. Its living conditions are very different from those in which most vertical flatfishes live – it inhabits a warm brackish water body, where the salinity of the water varies depending on the amount of precipitation and river flow. Often the rhombida enters the mouths of rivers flowing into the Eyre Gulf, but with the end of the rainy season it returns to the gulf, because it cannot live in silted shallow rivers.
The body of this species is deep, diamond-shaped, with a blunted head and a wide trapezoidal caudal fin. The body color of Australian rhombida is mirror-shiny on both sides of the body, slightly darker and with a greenish tinge on the upper part. Dorsal and anal fins at the highest and lowest points of the body carry a series of elongated rays forming two string-like outgrowths, which makes the unpaired fins of a fish look like half-open wings of a bird. The pelvic fin is reduced and narrow: it is a saber-shaped formation of several rigid rays. During swimming, it is pressed against the front edge of the body and serves as a kind of keel. These signs indicate that rhombida is an excellent swimmer. Rhombida male differs from the female only by a leaner body and a less convex belly, especially during the spawning period.
Rhombida is also characterized by the asymmetry of the skull and the location of the gill covers at different heights – on the blind side, the gill cover is higher than on the sighted side. The left eye of this fish is about twice as large as the right; it is located on the midline of the body and is directed straight forward. The mouth of the Australian rhombida is wide, and the jaws are able to extend forward, capturing fish’s prey. This species feeds on small schooling fish and lives singly.
Australian rhombida spawns in the ocean south of Meganesia. To spawn, these fishes gather in small schools and leave Eyre Gulf. Spawning occurs near the surface of the water, during the day. Rhombidas gather in small schools numbering several dozen adult fishes. Fishes in the school are constantly on the move, and the sunlight sparkles on their sides. During spawning, rhombidas are easily excitable, and even a bird flying over the surface of the water makes these fish jump out of the water. When the excitement in the flock reaches its apogee, there is a rapid, literally explosive spawning. The fertility of the female reaches 200 thousand small floating eggs. The females spawn their eggs almost simultaneously, and the males immediately fertilize them, and this is the end of spawning. Fishes go deep and rest for a while, after which they begin to return to the Eyre Gulf singly or in small groups.
Pelagic fry of this species are predators that feed on small invertebrates and juveniles of other fish. Cannibalism is not uncommon among them, and adult fishes often eat their small congeners. Australian rhombid reaches sexual maturity at the age of 3-4 years; its life expectancy reaches 15-18 years.

The idea of the existence of this group of fishes was expressed by Simon, the forum member.

Black-winged cyclops flounder (Disparopsichthys cyclops)
Order: Flatfishes (Pleuronectiformes)
Family: Cyclops flounders, or Unequal-eyed flounders (Disparopsichthydae)
Habitat: tropical areas of Pacific Ocean, top layers of water.

In epoch of ecological accidents smallest inhabitants of Earth, plankton organisms, frequently suffer. But plankton community is one of the most important thing for the biosphere of Earth. The phytoplankton provides restoration of stocks of oxygen in atmosphere in greater degree, than tropical woods. And well-being of zooplankton infringes interests of the majority of inhabitants of ocean in various degree: some species completely depend on plankton as food, and others spend a part of life cycle in plankton. Therefore during mass extinction of plankton organisms at the boundary of Holocene and Neocene ocean inhabitants of thickness of water had died out after them, and in early Neocene their ecological niches appeared free. Therefore at once many species have started to take their place in ecosystem of ocean.
Among new inhabitants of open ocean representatives of various groups had appeared, but nevertheless flounders seem the most unexpected inhabitants of thickness of water. Despite of their specialization to bentonic habit of life, these fishes spend a part of life, soaring in thickness of water at the stage of fry. When in sea a plenty of plankton had appeared again, some survived species of flounders from coastal waters more and more “were late” at the stage of fry, and soon completely passed to life in thickness of water. So the separate family of flounders living in thickness of water had gradually evolved. But singularity of these fishes consists not only in habit of life, but also in anatomy: at these flounders there are eyes of different sizes. Such phenomenon in human epoch was known at some squids, but at vertebrates it was showed for the first time. However, flounders just differ in asymmetry of body; therefore eyes of different sizes do not look especially unnaturally at them.
Among these flounders there are approximately fifty-fifty left- and right-sided individuals. One eye has remained at these fishes on the side of body peculiar to it. It is small-sized and also looks directly upwards. But the second one moving in process of individual development to other side of body, as if had stopped halfway, having remained at the stage, characteristic for flounder fry: it is on the middle line of body. And this eye in many respects determines unusual and monstrous shape of these flounders. It is big, round, and also directed right forward. Therefore flounder also has received the name (in translation from Greek “Cyclops” means “round-eyed”). Due to the size this eye provides the excellent field of view. Besides it is mobile and can turn in eye-socket.
Mouth at all species of cyclops flounders is wide; jaws are supplemented with sharp teeth: these fishes are predators. Jaws are able to be slightly extended forward when the flounder grips catch – small fishes and large plankton crustaceans.
The black-winged cyclops flounder has short and wide body. This fish swims rather slowly, flapping by lengthened forward rays of back and anal fins. But if it is necessary, fish can swim with the help of tail fin waves. For protection against enemies the body of cyclops flounder has a line of small bone scutes with spike in the middle, placed on middle line of body along the eyed side. The blind side of body at these fishes is colored bluish color with strong shine. It masks fishes from an attack from below: the blind side merges with patches of sunlight on the water surface. The eyed side of body at cyclops flounder is motley – grey with brownish spots. On forward part of back and anal fins there are longitudinal dark grey strips. During spawning period at males of this species stripes on fins become velvet-black, and is had determined the specific name of fish.
This fish spends a lot of time above sea shallows, gathering to schools of some tens fishes. It feeds mainly by small fishes, shrimps and large plankton organisms.
The spawning takes place in top layers of water well heated by sun. It repeats two times per one year, and in warm years it may happen up to three times. During courtship rituals males gather to unisex flights. They “soar” under the surface of water, having opened fins, and involving females by black strips on fins, well appreciable in sunlight. They chase females ready to spawning by flights, simultaneously fertilizing eggs spawned by it. For one spawning the female can spawn up to two millions tiny grains of roe. Similarly to all flounder species this fish does not care of posterity.
Young fishes become sexual matured at the third year of life, and general life expectancy of this species makes up to 20 years.

Far from coast the close species of this family lives: flying cyclops flounder (Pterodisparoptichthys prolongisomus). It differs from black-winged cyclops flounder by features of anatomy: at it one abdominal fin is strongly advanced, and the tail fin has grown together with back and anal ones, as at soles. This flounder is more specialized to pelagic habit of life, than black-winged cyclops flounder. It swims quickly, flapping, as if by wings, by abdominal fin and muscled forward part of back fin which is detached from other fin. Like black-winged cyclops flounder, it is a schooling fish gathering to huge schools numbering hundreds and thousand of individuals. This fish never swims up close to coast.

Pipistrelle gurnard (Pelagotrigla vespertilio)
Order: Goblingfishes (Scorpaeniformes)
Family: Gurnards (Triglidae)
Habitat: Tanganyika passage, superficial layers of water.
Mass extinction at the boundary of Holocene and Neocene, caused by natural cataclysms, has put serious impact to population of plankton organisms. Sharp decreasing of their number has entailed extinction of plenty of species of fishes depending on them. Basically they were pelagic fishes. Inhabitants of sea shallow waters and rivers were luckier: ecosystems in which they lived, not so much depend on plankton, as communities of open ocean. Therefore in such places rather variable ichthyofauna, among which there were ancestors of pelagic fishes of Neocene, was kept.
The thickness of water was occupied basically by species from coastal waters though among pelagic fishes there are even descendants of ground fishes. One of such species is the pipistrelle gurnard. It is fish about half meter long, soaring in top layers of water of Tanganyika passage.
Wide pectoral fins “inherited” by pipistrelle gurnard from benthic ancestors, have acquired now other function: the fish moves in thickness of water, flapping by them, as by wings. Bases of fins became very strong and were displaced upwards that the body of fish began steadier at “underwater flight”. Bases of pectoral fins have grown together in solid bone structure serving as a basis for muscles, moving by fins. Free rays of pectoral fins (“legs”, characteristic for bottom-dwelling species of gurnards) became very long and thin: they have turned to organs of touch sense, with which help fish communicates with neighbours and scrutinizes floating objects. On them a plenty of bodies of taste is developed, therefore fish can find out, whether object interested it is edible, not snapping it. Because the pipistrelle gurnard became an active swimmer, its body began easier: it is very narrow and deep, swimming bladder began more voluminous, and characteristic bone armour on forward part of body is strongly reduced.
In the first back fin of the pipistrelle gurnard eight poisonous spikes stick up, and one more is in anal fin. Such protection permits fish to not be afraid of predators furrowing waters of Tanganyika passage. Threatening a predator, going to attack, the pipistrelle gurnard “stands on head”, having turned to it by back and having exposed forward spikes. Simultaneously it widely opens pectoral fins similarly to wings of butterfly, and flaps them, moving to a predator wave of water. If the predatory fish will venture to attack the pipistrelle gurnard, it may receive some strong stings of poisonous spikes.
The pipistrelle gurnard “sounds” the threat, uttering loud abrupt sounds. And to secure itself more reliably against further attacks, fish has characteristic bright colouring. Pectoral fins are bordered by black strip, and on their surface there is large red spot. The silvery body of fish has characteristic contrast pattern of cross velvet-black strips. On unpaired fins there are lines of large black spots. Such colouring will be remembered for a long time to the predator having had received sting of poisonous spikes of gurnard.
Certainly, contrast colouring of pipistrelle gurnard could frighten off from it possible catch if the gurnard should be predator, but this fish eats rather specific food. The pipistrelle gurnard eats the mucous and spineless invertebrates living in thickness of water - jellyfishes, comb jellies and salpas. The mouth of this fish can extend to tube when it attacks the next translucent prey. Teeth of pipistrelle gurnard are strongly reduced: they are similar to bunches of bristles sticking up at the center of top and bottom lips.
For feeding by such specific catch at this fish the interesting adaptation was developed: strong immunity to poisons of jellyfishes and siphonophores. Even very young small fish can “plunder” fatally poisonous for other fishes tentacles of siphonophores without harm for itself, gathering small animals caught in them. And the adult gurnard will to have eaten also feelers with great pleasure.
All life of pipistrelle gurnard passes in thickness of water, courtship games also take place here. Males of pipistrelle gurnard distinguishing from females by bone combs above eyes and wider fins, perform rolling “love serenades”. Sometimes between them short skirmishes flare up, at which males are “butting” with the help of combs. When the female full of eggs, swims nearer to the male, he begins to sing special “aria of the groom”, similar to chirring of cricket. If the female is ready to spawning, she joins the male, and fishes sing some time a duet.
Fishes spawn plenty (about 300 thousand) small grains of roe and after that do not care at all of destiny of posterity. Glass-transparent fry spends first two months in plankton, eating larvae and eggs of other fishes. Frequently they join the large jellyfish and keep under its bell, from time to time stealing the small catch caught by it. At the age of three months at them adult colouring starts to be shown – at first separate pigmented areas appear, merging later to strips. Half-year old fish reaches length about 30 cm and already can breed. Males at this time get red spots on fins – mark of sexual maturity.

Pale gurnard (Parvitrigla relicta)
Order: Goblingfishes (Scorpaeniformes)
Family: Gurnards (Triglidae)
Habitat: relict salt lakes of the Mediterranean basin.
Pale gurnard is a descendant of one of the small gurnard species from the Mediterranean Sea – most likely, of Trigla lyra. When the sea dried up during the Ice Age at the turn of Holocene and Neocene, the ancestor of the pale gurnard managed to adapt to life in conditions of variable salinity and limited resources in one of the few habitable relict lakes at the outskirts of the Mediterranean hollow.
For fish, a lake in the middle of the desert is an analog of an island in the ocean for land-dwelling animals. Therefore, pale gurnard displays features characteristic of the evolution of island animal species. It is a small fish, the length of which reaches 20-30 cm. The body is elongated; the pectoral fins are very well developed. Caudal fin is quite large and, wedge-shaped, while the dorsal fin is low and long. The head is also elongated, with a small inferior mouth and thin shell plates. The eyes are relatively large, yellow in color, protected from above by thin bony “eyebrows”. The name of the species reflects the peculiarities of coloration: pale gurnard lacks the multicolored pattern of marine gurnard species of the human epoch. The general color is bluish, the pectoral and caudal fins are very light, and the dorsal one is dark gray. Rows of small white scales stretch along the sides. The lower rays of the pectoral fins turned into characteristic “legs”.
It is a benthic fish. Pale gurnard swims relatively poorly in the water column, but quickly crawls along the bottom with the help of modified fin rays, and only in case of danger swims with the help of tail. The soft coloring helps this fish to disguise itself against the background of sand.
The food consists of worms, snails, crustaceans, smaller fish and their eggs. The fish has an inferior mouth, and it crawls along the bottom, gathering its prey. Often this fish attacks small animals by hiding in the sand and attacking from ambush. The fish itself can fall prey of birds of prey like the salt hawk. In case of danger, this fish rushes to the depth, or quickly buries itself in the sand.
As the lake dries or fills with water, the population of these fishes migrates to the zone of habitual salinity. To get rid of parasites, fishes often enter the mouths of rivers supplying the lake and move upstream. When the lake shallows, fishes can survive by moving into the river; adults can easily survive life in fresh water for several months, but eggs do not develop in fresh water.
Spawning occurs in mid-spring, when the lake is replenished with water flowing from the Alps mountain range, and the salinity level stabilizes. At this time, pale gurnards gather in shallow water, in thickets of algae. At this time, males get pink, and sometimes red color, and a dark border appers on their pectoral fins. They become very aggressive, attacking each other and other animals, such as crabs. They often chase the shadow of a bird flying over the water. At the same time, males utter a variety of sounds – usually a monotonous long-lasting buzz, audible even on land. They estimate each other’s force by the strength of the sound, and it allows them to avoid direct conflicts with each other. Females also evaluate the volume and duration of the males’ “singing”. Having chosen a female, the male leads her into a dense thicket of algae, accompanying his courtship with a series of loud clicks. She spawns 1-2 thousand eggs in the thickets, and leaves the clutch, and the male remains to guard it. Despite his parental care, many eggs and fry become prey of various predators, mainly crabs. Fluctuations in the lake level and associated changes in water salinity are also dangerous for eggs and juveniles. When the fry begin to swim, the male leaves them. For the first weeks of life, young fishes stay in the thickets.
Sexual maturity comes at the age of 3 years; life expectancy is up to 15 years.

This fish species was discovered by Mamont, the forum member.

Impostor boxfish (Platyostracion imitator)
Order: Tobies (Tetraodontiformes)
Family: Boxfishes (Ostraciidae)
Habitat: reeves of Pacific Ocean in tropical and subtropical zones.
Reeves prospering in well warmed up shallow waters of Pacific Ocean are a place of congestion of various species of live creatures. The variety of food sources and shelter abundance results in appearing of numerous species of live creatures, and many of them may be strictly specialized. At reeves as rather peaceful plant-eating or omnivorous fishes and crustaceans, as obvious predators of various species live. Small inhabitants of reef stay in very unprofitable position – they risk to appear anyone's dinner almost every minute. Therefore till the evolution process they had developed various strategies of survival.
One species of crustaceans, the grooming crab, is in relative safety due to the role playing by this one at reeves. This crustacean renders fishes of cleaner service; therefore the majority of fishes does not attack it, and even trusts this animal to clean vulnerable areas of body like gills and eyes. Imitation of such well protected species is a good way of survival, and one fish had dexterously developed the imitaion of the shape and movement of grooming crab, avoiding attacks of the majority of reef inhabitants. It is the representative of brightly colored and protected by firm shell boxfishes, the impostor boxfish. This fish imitates the grooming crab, but does not render body clearing services to fishes. Similarly to it in Holocene some sea blennies imitated cleaner wrasses using the protection of these fishes from predators. But sea blennies attacked fishes, and this boxfish only uses protective similarity in coloring and behavior to the grooming crab to which practically all fishes of reef behave favourably.
The impostor boxfish is a small fish: length of its body is about 8 cm. The body of this fish is covered with armour, flattened and looking rounded at sight from above. Coloring of impostor boxfish is the main feature of its masking. Fish is almost entirely black, and its back is white with black spots. Pectoral fins of impostor boxfish are wide and fan-shaped, having red spots on edges. When the fish is swimming above the reef surface, movements of its pectoral fins are similar a little to movements of swimming legs of grooming crab.
Eyes of this fish are glogged, mobile and “frog-like”. Due to such feature fish can easily see everything happening behind it. The tail of this boxfish is very short, with a small fin serving only for turns. The impostor boxfish swims very slowly and tries not to depart far from reef where it is protected by instinctive behavior of other fishes not attacking the grooming crab. Despite of security this fish constantly keeps near to cracks and deepenings, hiding there when predators like the dorado croaker swim to reeves.
Impostor boxfish swimming among shells is very similar to grooming crab waiting for “clients”. But as against its arthropod prototype, this fish is not interested in cleanliness of fishes swimming around of it at all. Impostor boxfish eats small invertebrates biting them off from the reef surface by strong beak-like jaws. However, some most impatient fishes confuse the imitator and “original” and start to push this boxfish by head to drive its attention to them. Usually this fish does not react aggressively to these actions, but sometimes impostor boxfish should frighten off excessively importunate fishes. The disturbed impostor boxfish applies the reception characteristic to all its congeners: fish emits out poisonous liquid with strong irritating action which forces large fishes to keep aloof from the boxfish. Such feature of fish, strangely enough, is favourable not only to the boxfish, but also for crab: it suppresses possible aggression of “client” fishes relatvely to grooming crab. But nevertheless the impostor boxfish prefers to hide from large predators in crevices of reef.
The spawning of this species is paired and takes place at night. Male finds on reef surface small hole suitable by size, clears it and starts to involve females with the special crunching sounds. Female spawns eggs (about 400 tiny grains of roe) and at once abandons the clutch; male looks at eggs alone. It had to drive away from nest small fishes and crabs and to push away sea urchins. Protecting clutch, it can easily attack the fish exceeding its own size. For the period of clutch care male changes colouring – it becomes light yellow with dark irregular-shaped spots. This way it is not disturbed by fishes confusing it with grooming crab – some of them are much stronger than it and can ravage its clutch.
Permanent watch of the male on clutch lasts approximately till one week. At this time larvae hatch from eggs, turn to fry and start to swim out. They will lead about one month in plankton above the reef, and the majority of them will perish. Having managed to survive young fish returns to reef and settles in any shelter. The young growth of impostor boxfish has cryptic colouring – grey with black speckles. Till the growth speckles increase and merge, and the back turns lighter. The body of young fishes is short and almost cubic-shaped; later it extends and becomes disc-like. Having reached length of 2 cm, young impostor boxfishes start to simulate grooming crabs.

Armoured reefscraper (Scrapognathus armatus)
Order: Tobies (Tetraodontiformes)
Family: Boxfishes (Ostraciidae)
Habitat: tropics of Pacific Ocean, coastal reeves.
Reeves give a rich choice of food for animals living there. But on the other hand, abundance of food derivates a plenty of consumers, and as a consequence aggravates a competition between them. Therefore in such environment the appearing of various highly specialized animals eating only one or few kinds of food is possible. This strategy of survival has both strong, and weak sides. The greatest advantage of strict feeding specialization is almost complete absence of the competition to other species. And the basic lack is the dependence on an only source of food and impossibility of the passing to other food if the basic food vanishes. Nevertheless, such strategy of life is very common among reef inhabitants.
Reeves around of islands of Pacific Ocean are formed mostly by sponges and limestone-forming algae of various species. Coelenterates are presented here by not numerous species, and the great amount of limestone is delivered to reef with giant molluscs. At the surface of shells of large sea inhabitants the set of tiny creatures settles – polyps, molluscs, sessile crustaceans. They catch and filter from water food particles and tiny planktonic animals, and become food for other creatures.
The fish armoured reefscraper, widely settled in tropical zone of Pacific Ocean, eats small sessile animals. It slowly creeps on surface of reef, leaving behind itself a surface cleared of sessile animals.
Reefscraper has original appearance, characteristic for benthic fishes. It has wide and flattened body of rounded outlines, about 15 cm long. Head is covered from above with strong bone armour. This fish has camouflage colouring of the top part of a body – greyish-green with brown spots on head. The bottom part of body, imperceptible at usual position of fish at the bottom, on the contrary, has very appreciable colouring – it is white with set of black irregular-shaped lines forming wavy labyrinth-like pattern.
Eyes of armoured reefscraper are shifted upwards and are located in “openings” of the armour. They are mobile and can turn in various sides, like at mudskipper fishes (Periophthalmus). In case of danger fish retracts eyes under the armour. Gill apertures are also shifted upwards and open behind eyes in the same openings of the armour. They are protected by skin valves. Armoured reefscraper has inferior mouth. Instead of teeth lost a long time ago even by ancestors of this species, in jaws strong bone plates grow, with which help fish scrapes food from the surface of reef. The digestive path is long; in forward part (before the stomach) it has sac-like expanded outgrowth with strongly extensible walls.
The body of armoured reefscraper is covered with small armour plates, and on sides there are two or three lines of cross crests formed by their outgrowths. The stomach is not protected by armour and is covered with extensible skin. In case of danger fish hides into the crevice of reef and is inflated, swallowing water in pharyngeal sac. At inflated fish crests on sides rest against walls of refuge and prevent the predator to pull it out.
Armoured reefscraper is not famous in its abilities to swimming; therefore it keeps mainly near shelters. Usually armoured reefscraper slowly creeps on surface of a reef, cleaning off various tiny sessile animals and the top layer of growing limestone-forming algae from the surface. Moving by transparent pectoral fins shifted upwards, this fish presses body against the surface of reef. The body of fish seems strange, because weak and short tail fin is skewed upwards and inactive. When fish is quiet, it is closed, but if the congener interferes on the territory of fish, it stretches tail fin, and at this moment its contrast colouring becomes appreciable – black cross strokes on white background. The tail fin does not help fish in swimming, and its function was undertaken with well advanced anal fin with muscled basis. Frightened by bottom-dwelling predators, this fish can make sharp forward rush. Due to the shape of head it emerges above the reef, and then in process of decrease of speed slowly falls on the bottom.
This fish lives in warm climatic zone where seasonal changes are not expressed. Therefore the courtship season at these fishes stretches for all year. Male of armoured reefscraper is smaller a little, rather than female, but its colouring is more contrast. Male ready to spawning gets dark colouring: its back becomes black, and on this background shining yellow eyes are clearly visible. It displays himself to the female, having inflated body and swimming above the bottom. Thus the pattern on its stomach becomes clearry appreciable. As a sign of submission female turns paler and becomes bluish-gray.
For spawning male gnaws out in substratum a hole of the size almost equal to outlines of its own body. Female spawns there up to 5 – 6 thousand eggs, and male begins protecting of clutch, covering it by the body. He ventilates clutch with an original way: having slightly opened gills, fish gathers water in mouth, and then, having closed branchial valves, “blows” water under body, to the clutch. In this way male is on duty near the clutch within five days. For this time from eggs fry hatch and spend in nest about one day. Then young fishes pass to independent life, and male abandons the nest.
Young fishes have normally advanced tail fin. But as they grow, the back fin is shortened, and anal one expands and turns shifted back. Tail becomes simply the “flag” which does not take part in movement. Metamorphosis is finished at the second month of life. In same time fish gets characteristic camouflage colouring. Pattern on stomach and striped colouring of tail appear only when sexual maturity comes, at the age of 8 months.

Great crownfish (Astrosoma medusiphaga)
Order: Tobies (Tetraodontiformes)
Family: Crownfishes (Astrosomidae)
Habitat: Pacific Ocean, subtropical and warm-temperate areas of Northern hemisphere.
Mass extinction of pelagic fishes of global ocean has resulted to situation, when in few millenia at once the set of ecological niches appeared free. Till this original period of “ecological anarchy” a lot of species of coastal and bentic fishes began to adapt to pelagic habit of life. During the subsequent millions years some genealogical lines superseded others, and a number of such lines has remained only the small number of well adapted variants successfully competing to representatives of other groups.
The amazing species of pelagic fishes lives in top layers of water at the north of Pacific Ocean. At first sight it is very difficult to define fish in this one – the body shape of this creature is so atypical. But some attributes obviously specify a place of this species among fishes – short tail with fanlike tail fin, large mobile eyes, pair of branchial apertures covered with skin valves, and continuously wavying fins – back one, anal one and the pair of pectoral ones. This fish is great crownfish, the strange pelagic representative of family descended from boxfishes (Ostracyonidae).
The body of great crownfish has outlines atypical for fishes. It is strongly extended, covered with bony armour, as at ancestors from boxfish family. But the shell of this fish is adapted to passive soaring in thickness of water. It has oval outlines and is strongly extended – the width of fish concedes to length only a little. Diameter of body reaches 90 – 100 cm, and sometimes fish may be larger. Some pairs of long and pointed bone spikes symmetrically sticking above eyes, before branchial apertures, on sides of the body and on each side of short tail give this fish similarity to crown. Tips of these thorns are directed from the centre of a body like beams, and slightly raised upwards. The length of spikes reaches 40 cm. One more small pair of spikes grows at the basis of tail and is directed back and a little to sides. Such means of passive protection help fish to avoid an attack of sharks and other predators, because it complicates their attack. The back of fish is covered with strong armour in which there are only apertures for eyes and rabbet in back part of body for back fin and tail. The bottom part of body is covered with armour made of separate plates. On sides and stomach of fish plates are supplied with short thorns. Skin between plates is easily stretching, and fish can inflate stomach, swallowing a plenty of water in special outgrowth which branches from the gullet and stretches under skin along the stomach. Colouring of this fish is bluish-grey; tips of thorns are white. On back of fish the small number of dark spots is scattered; male has greater number of them, rather than female. Fins are transparent.
Additional contrivance of passive protection is the poisonous liquid of brown-yellow color; fish emits it out from the special bladder opening to cloaca. It is especially toxic for cephalopods, and with its help fish protects itself from attacks of squids at the most part of life cycle when it becomes large enough to represent interest as food for them.
Armour strongly reduces mobility of fish, and great crownfish belongs to plankton despite of the size. To reduce weight of body and to improve buoyancy there are many cavities filled with porous bone tissue impregnated with fat in armour of fish. Due to it fish easily soars in water, directing the movement with the help of fins. Usually this fish swims, making wavy movements by short and rounded pectoral fins. If it is necessary to swim faster, great crownfish uses back and anal fins. Tail serves only for turns. Tail fin is short and its basis is wide and fleshy.
Great crownfish is the true pelagic fish, and appears in coastal areas only after long storm. It eats jellyfishes and shrimps, frequently eating large jellyfishes in common with symbiotes living on them and prey pasted to tentacles. This fish has no teeth, and two sharp horn plates are advanced instead of them.
Great crownfish is not aggressive to relatives, but prefers to lead solitary habit of life. This fish forms pairs only to short time of spawning. Male is smaller, than female. At the meeting with female ready to breeding he quickly changes colouring and turns ink-violet with white tips of spikes. He swims around the female, displaying himself and being ready to recede before aggression from her side at any moment. If the female does not show aggression, male begins the following stage of courtship. He swims on the female from above, and presses her by the body, trying to “plunge” her. If female dumps him, male may snap at one of her spikes and hang on it. Having proved its physical perfection, male swims up from female’s body and fishes swim together till some time, and then spontaneously spawn the true cloud of eggs (up to one million ones) and soft roe. Female can repeat spawning up to three times per year, but each time the amount of eggs becomes lesser. In winter time fishes are fattened.
Parents do not care of the posterity. Larvae of great crownfish develop in plankton and undergo significant change of the shape. At first their body is similar to body of usual boxfishes, later lateral edges expand and body becomes disc-like, facilitating the soaring in water. At the size of about 4 cm poisonous gland develops at fish. And at the length of about 6 cm on the body of fish spikes giving the characteristic appearance to adult individuals start to form.

Xenofugu (Xenofugu rapax)
Order: Tobies (Tetraodontiformes)
Family: Tobies (Tetraodontidae)
Habitat: Japan Islands, the south of Big Kurils, lower reaches and river mouths.
Tobies (Tetraodon) of Holocene epoch were basically heat-loving sea fishes and frequently inhabited reeves. But some species frequently settled in rivers and could pass a complete life cycle in fresh water. Many freshwater species of these fishes lived in Holocene in tropical and subtropical latitudes at vatious continents. All tobies are rather heat-loving fishes, therefore till the ice age at the boundary of Holocene and Neocene their number had decreased, and fishes had receded from high latitudes to equator. In Neocene when the climate turned warmer, the new moving of descendants of survived sea tobies to extending subtropic areas began. New freshwater species of these fishes related to sea ones had gradually appeared.
In rivers of Japan Islands one of toby species occupied an ecological niche of medium-sized predator. This fish is named xenofugu – it shows that this creature is not connected by direct relationship with the toby known in human epoch named “fugu” in Japan.
Length of this fish is about half meter. Xenofugu lives in rivers, but occasionally swims out to sea. In spring, till the period of heavy rains, when the top layer of water is considerably freshened, these fishes can swim far in sea and cross through rather narrow sea passages, migrating from island to another one. Therefore at all islands forming continuous circuit along the northwest coast of Pacific Ocean the same species of this fish lives, not forming local forms. In warm years these fishes swim far to the north – separate fishes meet even near southern coast of Kamchatka. They can make some generations in rivers of peninsula but they managed to settle here for a long time only once.
In rivers of Kamchatka where water is warmed up by volcanic heat, there is one stable population of this species ranked as a subspecies - volcanic xenofugu (X. rapax vulcanophilus) differing from the basic species in smaller size (about 20 cm long) and dark colouring.
Body of xenofugu is extended; it has lost rounded shape characteristic for these fishes. The head of this fish is similar to frog’s one: it is wide and flat with glogged “frog” eyes able to turn various sides. The back part of body is compressed from sides. Back and anal fins of fish are the basic movement organs. They are shifted back, and their bases are strong and muscled, especially at anal fin. Tail fin is fan-shaped and short. As at all tobies, it serves only for turns. Xenofugu swims slowly, but can make fast single rushes for catch. Usually it is inactive and prefers to arrange ambushes at the river bottom.
Colouring of top side of xenofugu’s body is cryptic: on grey background there are large and small brown spots and many tiny white points are scattered. The bottom side of fish’s body is snow-white. At volcanic subspecies from Kamchatka top of body is dark grey with black speckles, stomach is bluish-grey, and near eyes there are two white spots.
This fish is able to puff with the help of intestines outgrowth – such feature is characteristic for family. But xenofugu makes it only at threat of life or till the courtship displays. The skin of fish is soft, elastic, covered with thick layer of slime, and on stomach the set of short spikes grows. When the fish is puffed, they are protruded, protecting fish. Also this fish is very poisonous – in its tissues, interiors and peritoneum tetrodotoxine accumulates.
All tobies are carnivorous species, and xenofugu is not exception here: it eats invertebrates and fish. Being illegible in feeding, this species eats any animals which may be overcome – fishes, frogs, shrimps and crabs. Sometimes xenofugu attacks chicks of waterfowl and eats small mammals appeared in water. Teeth at xenofugu are lack as at all tobies; sharp osseous plates replace them. They are strong enough to crush firm crab carapace.
Usually this fish arranges ambushes at the bottom, being dug in sand and silt with the help of movements of anal fin and lateral movements of body. Having buried to required depth, fish throws on itself ground dust by strong pectoral fins and waits for approaching of suitable prey. The hidden fish even breathes very cautiously – having slightly opened mouth and branchial apertures, fish freely allows water to wash gills, only occasionally passing through gills a new portion of water. When small animal is approaching, fish jumps out from ambush and snaps catch.
Xenofugu passes all life cycle in fresh water. Separate fishes spawn in river estuaries where the influence of sea inflow is felt, but usually fishes breed in the same place where they live. Courtship displays are begun by males. The male of xenofugu is larger, rather than female, and plays a dominant role till the spawning. It finds and clears flat stone of dirt, and then begins courtship demonstrations near it. The smooth stone with small deepening from above is especially attractive to the male. It is a tribute to the past: tobies bred digging in sand a hole for eggs. Competing males puff and try to push each other out of chosen stone. Thus they are colored brightly: the background of top part of body brightens, and small spots merge to large dabs.
Eggs are laid on stone. Clutch may number up to 5 thousand tiny grains of roe. At this species constant pairs are not formed, and male right after spawning expels the female from the territory. Male carefully looks at posterity: it keeps near to the clutch, ventilates it by fin movements and throws out dust brought by current. Eggs of this fish are additionally protected from enemies: they are poisonous and colored bright yellow. Fry hatch approximately in two days, and abandon the nest three days later. Larvae of xenofugu are small and first time keep near the male. Male looks after posterity some next days, driving away from fry school even very large animals – it happens that the male in parental care zeal bites legs of large mammals came in water. Gradually fry leave the male and begin independent life. Young xenofugus hide and feed among plants. They grow rather slowly and reach the maturity approximately at four-year-old age.

Spotted brooding toby (Strumatofugu maculatus)
Order: Tobies (Tetraodontiformes)
Family: Puffers (Tetraodontidae)
Habitat: Meganesia, Arafura Lake.
During the movement of the Indo-Australian lithospheric plate to the north, the Arafura Sea was partially isolated from the ocean by a strip of mangrove forests. As a result, the waters of Arafura Lake have a lowered salinity level compared to the ocean, and in the ichthyofauna of Arafura Lake, fish species of marine origin still remain, that are able to exist and reproduce in conditions of reduced and variable salinity of water.
Among the groups of fish that thrive in Arafura Lake, there are brooding tobes, obvious descendants of marine fishes that lived at a higher level of salinity of the water even before the isolation of the sea and its transformation into a lake. They have adapted very easily to life in brackish water and even enter rivers flowing into it.
All species of brooding tobies have the ability to inflate their bodies when attacked by predators. They have an outgrowth of the digestive path that fills with water when fish is frightened or irritated, and has a peculiar shape: it is divided into two chambers located one in front of the other. The main chamber is located behind; it is filled with water when frightened and serves as a means of passive protection. The front chamber can be filled with water separately from the rear one. When inflated, it looks like a huge craw under the head of a fish – hence the scientific name. In the courtship season, the males of these fishes “butt” each other, inflating their “craws”. But the main purpose of this structure is to participate in the rearing of offspring: brooding toby males bear eggs in this chamber. Independently of other fish species, as well as of some amphibians, they have developed an adaptation for supplying embryos with nutrients: eggs placed in the brood chamber paste to the wall and appear overgrown with epithelial villi, into which blood vessels sprout. Due to the diffusion of nutrients from the male’s blood, the young of these fishes receive additional nutrition and are much larger than other species of the order with a similar size. Reproduction occurs throughout the year; fertility in large species is up to 200 eggs, in small ones – no more than 50 ones. Low fertility is compensated by higher survival rate of offspring.
All brooding tobies are bad swimmers. These are slow-moving fishes swimming due to synchronous wave-like strokes of the dorsal and anal fins; the short caudal fin serves only as a device for turns. Their body shape and proportions are similar to ordinary blowfishes, differing only in a wider mouth. All species are zoophagous.
Spotted brooding toby inhabits the coastal zone of Arafura Lake. It is a fish about 40-50 cm long, with a contrasting black and white body color – rounded black spots of various sizes are scattered on a white background. On the back and sides, the spots are larger and located closer; on the belly they are smaller and sparser. The throat and chest of the fish are colored orange-red, especially bright in males during their mating displays. Fishes of both sexes, during the defense of the territory, display their swollen craws to the opponents, and in males, during courtship, its coloration turns very intense, and the red color even spreads to the front part of the belly. This species feeds on small fish and crayfish.
Arafura Lake and its surroundings are home to similar species:
Dwarf brooding toby (Strumatofugu minimus) inhabits rivers and coastal areas of lower water salinity of the eastern part of the lake. The body length does not exceed 10 cm. The color is greenish-gray with small black specks; at the base of the tail stalk, there is a large ocular spot of blue color with a black border and a white “glare” spot. Real eyes of the fish are poorly visible among the spots on the body. The unpaired fins are transparent. The lower part of the body is white with black speckles, in the “craw” area the spots merge into intermittent longitudinal stripes. This species feeds on insect nymphs and small crustaceans.
Black-bearded brooding toby (Strumatofugu melanobarbus) lives in the coastal waters of the lake at various degree of salinity. Fishes of populations from lower salinity areas are smaller (about 20 cm), from saltier waters – up to 40 cm long. The coloration is bluish-gray with a darker “saddle” on the back. There is a large black spot with a white “glare” at the base of the dorsal fin. The lower part of the head and chest are black. The basis of its diet consists of benthic fish and crustacean species.
Mangrove brooding toby (Strumatofugu mangrophilus) inhabits the western part of the lake with a higher salinity level, including the channels in the mangroves separating the lake from the ocean. The body length is up to 60 cm; males are larger than females. The body color is yellowish-brown with dark brown spots on the back; the belly is white. The throat and the lower part of the head are covered with black spots, which stand out especially brightly when the “craw” is inflated. It is a predator that feeds on fish and any animals falling into the water from the branches of mangrove trees.

Reticulate disk-toby (Ostracyopsitta reticulata)
Order: Tobies (Tetraodontiformes)
Family: Armoured tobies (Neostracyonidae)
Habitat: reeves of tropical zone of Pacific Ocean.

Picture by Fanboyphilosopher

At the boundary of Holocene and Neocene the Earth has gone through great ecological catastrophe, as a result of which madreporarian corals, the main group of reef-building invertebrates, had been wiped off the face of the Earth. After them the richest fauna of reef animals, completely or in part depended on growth and prosperity of corals, had died out. In Neocene the place of coral reeves was occupied by ecosystems made by absolutely different organisms. And they had been developed by representatives of new fauna. Among inhabitants of reeves of Pacific Ocean disk-tobies are remarkable – brightly colored fishes swimming in schools. They are descendants of pufferfishes (Tetraodon), changed solitary way of life to social, and changed externally in great degree.
Body of disk-tobies is deep, has rounded outlines and is squeezed from sides. On back and stomach of these fishes body forms leathery keels promoting keeping of balance. All species of disk-tobies are small: in typical case about 20 cm long, and even smaller in the majority. But among them there are some “giant” species. They lack belly fins, and back and anal fins are shifted back. The fish swims forward due to their wavy movements, easily changing direction of movement and manoeuvring between sponges and mollusk shells. Tail fin of these fishes is short and leathery; it does not take part in movement, and with its help fish only makes turns. Pectoral fins are shifted upwards, and the centre of gravity at this fish is displaced downwards; therefore it is rather difficult even for dead fish to emerge up a belly.
The body of disk-tobies lacks of scales, but is protected against enemies with thin armour plates. They do not form any continuous protective armour as at boxfishes, and therefore do not complicate movement of fish. Between plates there are areas of extensible skin of contrast color. When fish is attacked, it swallows water, filling the special outgrowth of digestive path, turning strongly inflated. This feature is inherited by it from pufferfish ancestors. At inflated fish bright sites of skin stretch and become well appreciable. Skin of these fishes lacks of scales and has very bright and garish coloration with contrast strips and spots. It is warning colouring: meat of fishes is poisonous, and in addition in case of danger fish splashes out a jet of dark colored poisonous secretion.
Head of disk-tobies is short and deep; eyes are large. Jaws of fish represent a firm “beak”, with which help fish cracks fodder organisms with firm skeleton: sponges, armours of crustaceans and shells of molluscs. At the reeves disk-tobies of some species keep in large schools numbering up to fifty of fishes, and others live in families or solitarily. Each school, pair or single fish has the certain territory, and patrols it in process of growth of fodder organisms.
For spawning school of schooling species breaks to separate pairs, and solitary or harem species form breeding groups. At these fishes family is kept only for the period of spawning. For spawning fishes make nests in shelters, furiously protecting territory around of nest from congeners. Fry hatch in some days, and parents abandon the nest, forming new schools.
The young growth spends first time at the reef, grouping in numerous schoals of equal-sized ones. As they grow, they join schools of adult fishes, or (in case of solitary species) occupy a certain territory at the reef.
Reticulate disk-toby is a schooling species of fishes and keeps in congestions numbering up to hundred of fishes and more. It is one of medium-sized species; the length of adult individual may be no more than 35 – 40 cm, and usually smaller. Similarly to all schooling disk-tobies this fish has rather dim colouring: back and sides are blue; on bottom part of body there are light green spots separated by dark intervals forming characteristic mesh pattern. When the disturbed fish is inflated, dark skin between plates of armour is stretched, and fish becomes much more appreciable, displaying itself to predator. The iris of the eye is light, but on tail fin there is dark spot of “false eye”. This species eats sedentary worms and sponges, and bone plates on its jaws form firm “beak”.
At the reeves of Pacific Ocean close species live:
Parrot disk-toby (Ostracyopsitta psittaculus) is the smallest species of the genus: the adult fish reaches the length of about 5 cm. In body shape and colouring this fish resembles coral butterfly fishes of genus Chaetodon died out to Neocene. Body of this species is deep and strongly laterally compressed. Colouring of fish is contrast, black with big white spots (at mature fishes it resembles more any black grid on white background); unpaired fins are transparent, tail fin is fan-shaped and has red border along the edge. Head of fish of any age is black with large dark eyes and red strip around of “beak”. This fish keeps solitarily in cracks of reef and eats small crustaceans. Each fish of this species has territory with shelters where it hides in case of danger. If the enemy tries to take fish from it, this disk-toby inflates body and get densely “jammed” in shelter. This species actively protects territory against congeners, uttering squeaky warning sounds.
Honey disk-toby (Ostracyopsitta melisoma) is one of medium-sized fishes: body length of adult individual is about 20 cm including tail. This fish is named because of characteristic colouring: on yellowish-brown background on head, breast and stomach there is brown mesh pattern, remotely similar to honeycombs. Unpaired fins are transparent, and it gives to fish original appearance. Honey disk-tobies settle at the reef solitarily and eat mainly polyps, small snails and other soft-bodied invertebrates. Honey disk-tobies protect territory against congeners, uttering abrupt clicks.
Mourning disk-toby (Ostracyopsitta funebris) belongs to medium-sized species: it is up to 30 cm long. This fish has black colouring with white spots of various sizes near the tail stalk – at different individuals their number and sizes vary. Lips are also snow-white. Mourning disk-tobies keep at reeves in schools numbering up to hundred of fishes and more, and eat various small animals. They are rather peaceful to congeners; schools of this species have no constant territory and easily unite and break. The schooling behaviour provides reliable protection: mourning disk-tobies can actively defend against predators, biting them strongly. And the school of these fishes can drive back even very large predator. Contrast spots around of lips warn a predator of ability of this fish to defence. Spots on tail represent the “amplifier” of this colouring, creating the illusion of protection from both ends, and do not give a predator of an opportunity to orient and to attack fish from unprotected end.
Moonlight disk-toby (Ostracyopsitta lunaris) is the largest species of the genus: the length of its body is more than half meter. This fish has rather modest caesious color with metal shade. Only on sides there are the sites of dark skin, forming irregular mesh pattern and strongly stretching when fish displays itself to aggressor. Also on tail fin of fish there are some round black spots. Fishes of this species live in small schools numbering no more, than ten individuals, and swim rather slowly. This species eats mainly invertebrates with firm covers: crustaceans and molluscs. Occasionally these fishes can attack wounded and ill fishes, but do not pay attention to healthy ones.

Dirigible fish (Paramola zeppelin)
Order: Tobies (Tetraodontiformes)
Family: False sunfishes (Paramolidae)
Habitat: reeves of Pacific Ocean.

Picture by Alexey Tatarinov
Improvement by Carlos Pizcueta (Electreel)

In Neocene ecosystems of tropical sea shallows developed practically anew. Coral reeves of Holocene represented the fine balanced community in which many species occupied very strictly shared ecological niches. Thus, during the global ecological crisis at the boundary of Holocene and Neocene, when the significant part of species of reef-building corals had died out or became a rarity, the huge amount of reef inhabitants had become extinct.
In Neocene highly productive communities of sea shallows had appeared again. Like ones of human epoch they are populated with numerous species of fishes and invertebrates. In human epoch tobies (Tetraodontidae) and parrot fishes (Scaridae) were specialized durophagous species – animals eating organisms having firm body covers (crustaceans, molluscs) or internal skeleton (corals). At reeves of Neocene the niche of durophagous species is occupied by other fishes. In Indian Ocean it is huge crushing trunkfish (Titanostracion destructor), and at reeves of Pacific Ocean its distant relative, massive dirigible fish, lives.
The length of this fish reaches 160 cm at weight of up to 120 kg. At the first sight on dirigible fish it is possible to note its obvious similarity to sunfishes of human epoch (genera Mola, Masturus and Ranzania). But Holocene sunfishes, peaceful devourers of plankton lived at open ocean, had died out a long time ago, and their place in ecosystems was occupied by freakish creatures belong to other systematic groups. Dirigible fish is similar to sunfishes, but is only their very distant relative. It descends from tobies (Tetraodon) of Holocene epoch.
The body of dirigible fish has the shape close to cylindrical in cross-section. Head of this fish is short and deep, and strong jaws are located in its bottom part. Instead of teeth in mouth very firm plates grow, with which help the dirigible fish cracks shells and armours of animals used for food. The skin of dirigible fish is colored gray-blue with darker irregular-shaped spots.
Development of fins at dirigible fish gives to it significant external similarity to sunfish, but it is a result not of direct relationship, but of parallelism in evolution. Tail fin of dirigible fish is reduced up to leathery vertical plate with rudiments of fin rays. Tail stalk of fish is short and expanded; therefore back part of fish between back edges of back and anal fins seems cut off on to a vertical. The back and anal fins having lobe-like shape with rounded tips are principal organs of movement of dirigible fish; during the swimming they move wavy. Dirigible fish can freely swim back to front, and, despite of large size, is able to maneuver at the reef easily. It swims slowly as eats inactive food – mollusks (bivalves and gastropods), and also large crustaceans. Swimming fish resembles dirigible balloon – hence the specific epithet in scientific name and common name of fish. Shortly before storm dirigible fishes leave reef and swim down to depth.
Life at the reef is full of dangers. In Neocene in tropical zone of ocean sharkodiles (Carcharosuchus deinodontus), monstrous sea crocodiles belong to last representatives of the group rule. The adult sharkodile avoids appearing in shallow water, but younger individuals frequently hunt at reeves. Dirigible fish is too sluggish to escape from them in flight; therefore it relies to passive protection. Skin of dirigible fish is very firm and viscous - at the bite young sharkodile may simply break some teeth. Besides large bladder containing poisonous dark brown liquid opens to cloaca of dirigible fish. The basic poisonous substance is tetrodotoxine: ability to produce it is inherited by dirigible fish from tobies, its ancestors. Muscles of this fish also contain a plenty of poison.
Dirigible fish breeds, laying at the reef a plenty of ground eggs. Male chooses suitable site of reef, digs out or deepens a hole at the bottom, and starts to involve the female, uttering sound similar to gnashing with the help of jaw plates. Its colouring becomes very contrast: background colouring turns blue, and spots blacken. The female spawns in nest prepared by male up to 500 thousand of tiny eggs, and male protects the clutch within three days while fry will start to swim.
Young dirigible fishes are not similar to adults, and resemble fry of typical tobies more. They have tail, and tail fin is normally advanced. As fishes grow, the tail part of body simply stops in development and the partial reduction of fin begins.

Firemouth (Abyssodon flammeostomus)
Order: Tobies (Tetraodontiformes)
Family: Abyssal tobies (Abyssodontidae)
Habitat: Pacific Ocean, depths about 2000 meters.

Picture by Carlos Pizcueta

The majority of biotopes of Earth directly or indirectly receives energy of the sun. Only at the bottom of ocean near to underwater volcanos there are complexes of the live organisms existing due to geothermal processes. But they look exception in the biosphere dependent on the sun. Even in places where the sunlight is not present, live creatures depend on it. One of such ecosystems is developed in ocean depths. Sea water quickly detains sunlight, and photosynthesizing organisms are not found in depths of ocean. But inhabitants of depths completely depend on efficiency of top layers of water – they eat falling from above dead organisms and their own neighbours making vertical migrations. Therefore in time of “plankton accident” the mass extinction of deepwater fauna happened. After disappearance of typical deepwater forms new species, descendants of coastal species had started to occupy their place in ecosystems of Neocene.
Pufferfishes, or tobies (Tetraodon), very adaptive predators, were among settlers in depths. Obviously, they had settled in depths of ocean from continental slopes, then “took off” a bottom and pased to pelagic life (possible, ancestors of deep-water anglerfishes Lophiiformes had done the same way before them). One descendant of deep-water tobies had turned to specialized predator of thickness of water. The fish had got characteristic features of deepwater inhabitants: its bones became soft, and around of mouth organs of luminescence had appeared. For this feature the fish has received the name “firemouth”.
The length of this fish does not exceed 20 cm – as a rule, deep-water fishes do not reach the large size. Body of firemouth is soft, and its consistence is tender. It is rounded and also seems “bloated”: when the fish is swimming, the skin slightly waves. In skeleton bones are substantially replaced with cartilage – it is the typical feature of deepwater fishes. Eyes are very small, and sight of firemouth is bad. But lack of sight is compensated by very much advanced sense of smell. The sensitive area of olfactory holes is stretched to internal surface of big skinny outgrowths surrounding nostrils. They are very movable, and also work as “ears”, helping to the fish to orient itself in darkness of depths. Skin of fish is elastic and easily extensible. It is grayish – pink and seems chemically decoloured. Through skin of firemouth internal organs and large blood vessels are visible. The skin of tobies living in shallow waters is covered with a plenty of corneous spikes, which rise when fish is inflated with water or air. On the body of firemouth some corneous plates with sharp spikes in the centre had remained from this adaptation.
All deepwater fishes are predators or scavengers – herbivorous species among them are not present. At firemouth jaws are large, surrounded with a ring of small organs of bioluminescence. Instead of teeth at firemouth sharp plates grow as at all representatives of the order: it is the firmest part of fish body. With the help of luminous organs firemouth beckons fishes and invertebrates right to the mouth. This predator kills catch by characteristic bite in head and swallows entirely due to very extensible stomach.
The basic organs of movement of firemouth are back and anal fins – fish swims with the help of their waves. At these fins there are mobile muscled bases, and vertebrae in places of muscle attachment have big vertical outgrowths. Tail fin is considerably reduced, continuing the tendency common for representatives of the order. Pectoral fins of fish are shifted upwards and help to turn on the spot. Pushes of water through branchial apertures help this fish to move forward.
At deep-water fishes males, as a rule, are much smaller, than females are, and some species even became hermaphrodites. At firemouths “equality of gnders” is kept: it is connected with the distribution of roles of fishes in the spawning. Spawning at firemouths occurs in pair, and some features of breeding inherited from coastal ancestors were kept. The majority of pelagic fishes differs in great fertility – they produce huge amount of tiny eggs, and do not care any more of posterity. At firemouths the female lays only some hundreds of rather large eggs (their diameter is up to 3 mm). Fishes find each other by smell and flashes of light. Photophores of the female ready to spawning emit blue light seen from apart. Male finds female and begins courtship dance, touching to the female by fins and slightly biting her tail. The female pastes eggs on stomach of the male, and simultaneously he fertilizes it. At the culmination moment of courtship games when the female starts to spawn eggs, male emits cloud of soft roe, and pair of fishes “spins” in it. At this moment the fertilisation happens. Fertilized eggs are pasted to skin of the male and dead grains of roe peel off later. The male only carries eggs on itself, but does not look after posterity. Hatching fry at once leaves it, and begins independent life.

Crownmouth (Coronostomichthys constellatio)
Order: Tobies (Tetraodontiformes)
Family: Abyssal tobies (Abyssodontidae)
Habitat: northern part of Pacific Ocean, depth about 2000 meters.

Picture by Timothy Morris, colorization by Alexander Smyslov

Deep-water habitats entirely depend on efficiency of top layers of water. Therefore in epoch of ecological crisis at the boundary of Holocene and Neocene mass extinction has mentioned deep-water fauna even in greater degree, than shallow water one. Actually, in Neocene deep-water fauna began to form practically from zero. At this time in abyss representatives of groups of animals earlier not met in this habitat began to appear. Among new species of deep-water fauna representatives of tobies order, which were shallow sea and freshwater forms earlier, have appeared. In the course of evolution tobies had developed life in sea depths, becoming the similarity of anglerfishes (Lophiiformes) known in Holocene epoch.
Among tobies there are some deep-water species. One of them is firemouth, whose mouth is surrounded with luminous organs. It has close relative, crownmouth, differing in more specialized organs of luminescence. At the crownmouth luminous organs are located around of mouth on long elastic stems, forming the “crown” (hence the name of fish). With the help of these luminous organs crownmouth is able to imitate various sea animals. Having hung in thickness of water headfirst and having lowered luminous bodies like the closed umbrella, crownmouth imitates luminous deep-water jellyfishes. The bases of stems of luminous organs are mobile, and sometimes fish moves by them chaotically, involving catch. At this moment they are similar from apart to congestion of small luminous animals like shrimps. Hence the specific name of fish “constellation”, meaning “constellation”. Luminous organs produce blue light which is seen in sea water from apart. Having own “illumination”, crownmouth differs in weak sight, but sense of smell at this fish is advanced very well.
Crownmouth is sluggish swimmer. It is fish of spherical form with short fins and wide mouth. Length of body of crownmouth is about 15 cm; tail of fish is short with wide fin. Osseous plates, replacing to all tobies absent teeth, at crownmouth are more advanced, than at related firemouth: they form some pointed outgrowths like teeth. These plates are the strongest part of body, and other skeleton of fish is soft, gristle-like and elastic. It is the prominent feature of deep-water fishes appeared independently at various unrelated groups of deep-water fishes.
The skin of fish is colored black – so crownmouth is not appreciable in light of its own fires. As well as all deep-water animals, crownmouth attacks various catch, as opposed to fishes of shallow waters which can be specialized stenophagous species. Crownmouth eats any catch which it is able to swallow – usually it eats fishes up to 20 – 25 cm long, octopuses and other large invertebrates. Teeth-like outgrowths on jaw plates help fish to kill quickly any catch – they equally easy break shell of shrimp, pierce skull of fish or cut soft viscous flesh of octopus. To kill catch is only half of hunting success; it is not less important to manage to use it. The crownmouth does not encounter difficulties, swallowing catch. Alternately working by jaws and alternately sticking in catch jaw plates, this fish as if “stains” itself on catch, thus its mouth is strongly stretched. Jaws of crownmouth are not adapted to biting off food, therefore any prey, even the largest one, is swallowed by this fish entirely. In the other hand, due to stretched skin and soft bones it can swallow various animals. Catch goes on in stomach, which also is strongly stretching.
It is not only catch under water. Predators also come involved with light of fires of crownmouth, but the fish is able to protect itself from them. It uses the reception traditional for tobies: fish strongly puffs body, swallowing water. The skin of crownmouth is covered with plenty of corneous thorns. When the fish is inflated, they rise and spread wide. It is very effective protection - at many predators there are easily extensible mouths and stomachs which are easy for injuring. Therefore the predator, as a rule, refuses to attack prickly fish.
The male of crownmouth is smaller, than female. In depths of ocean there are no seasons, and crownmouths can spawn at any time. The male swims better, than the female – its body is more oblong, and stems of luminous organs are shorter. It searches for the female ready to spawning, by smell. Having found out the necessary individual, the male executes for it special “presentation” with the help of fires; it is necessary to prevent the attack of the female. Also he emits from cloaca the special chemical substance, braking aggression of the female.
Spawning eggs, fishes nestle stomachs against each other; thus the female is overturned by back downwards. Eggs of crownmouth are pelagic, with fat drop. In clutch there are some tens thousand very small eggs. Spawned eggs at once emerge, float through cloud of soft roe emitted by male, and within several hours rise to the surface of water. At this time a lot of eggs perishes from various predators. Fry develop in top layers of water, in plankton. Young crownmouths are absolutely not similar to adult fishes: they are creatures with flattened triangular head making about half of length of fry. Corners of head, sticking back, are extended to long strings – it facilitates soaring in thickness of water. Young crownmouths are passive plankton predators. As they grow, fishes swim down in deeper layers of water and get shape, characteristic for adult fish. Life expectancy of crownmouth can make about 18 years.

Chameleon clingfish (Labresox chamaeleonoides)
Order: Clingfishes (Gobiesociformes)
Family: Clingfishes (Gobiesocidae)
Habitat: reeves of Pacific Ocean, Hawaii.
Reeves in tropical zone of seas are a place of concentration of various live beings. Reef boicenose includes many kinds among which there is strict competition. During the evolution process at reeves various highly specialized species had appeared – thus the competition between them is weakened. At reeves there is one especial ecological niche which is occupied by cleaner creature, eating ectoparasites of other reef inhabitants. In human epoch fishes of wrasse family (Labridae) and some species of shrimps realized sanitary service at the reef. At the reeves of Neocene epoch crabs had appeared among cleaners – one representative of swimming crabs (Portunidae) family. Besides it, chameleon clingfish, the specialized representative of the group of inactive fishes characteristic for coastal zone, renders services of cleaner to fishes. Hence its name: “Labrus” is the scientific name of wrasses, fishes rendered cleaner services to other fishes in Holocene epoch.
Chameleon clingfish is rather small kind of fishes – its length does not exceed 8 – 11 cm. It has flattened body supplied with strong sucker on belly side, formed by grown together bases of abdominal fins. The head of this fish is strongly flattened and rounded in front; mouth of scraping type is located on its bottom side. Nostrils are positioned between large glogged eyes. Their site is marked by two bushy nasal valves – skin outgrowths. Unpaired fins of this fish are grown together in unite structure bordering back part of body of this fish.
Colouring of chameleon clingfish is bright and appreciable: yellow with large black points. But fish gets such colouring only in rest, which happens very seldom at its habit of life. This fish is completely harmless, and its main protection against enemies is a skill to hide and to change colouring, skilfully masking in imitation of colors of environment.
Chameleon clingfish is specialized to body clearing of large fishes. Usually it settles near well appreciable elements of reef – near separate shells or blocks of limestone. Here it waits for “clients” – large fishes requiring for clearing of skin from parasites. They find out this fish by its specific colouring, and, having swum up to it, freeze, having turned sideways to the cleaner. Having received such signal, chameleon clingfish sticks to their sides and begins clearing of fish. Thus it changes color, imitating colouring of served fish. Having cleared fish from parasites, this fish “jumps off” and becomes bright again.
Mouth of chameleon clingfish is scraping; lips are covered with numerous corneous bristles, helping to clear skin of the client fish. Due to flat head this fish can get under operculums of the client fish to clear gills of parasites and dust.
Chameleon clingfishes lead strictly solitary habit of life. They occupy small territories, and food comes to them on sides of client fishes itself. But in any case they do not suffer the presence of congeners and competing animals leading similar way of life (for example, cleaner crabs), and behave to them aggressively. This fish is tolerant to congeners only when they are ready to spawning. This fish species is hermaphrodite, and easily changes sex during the life, sometimes multiple times within one year. At the preparation for spawning the breeding pair forms of fishes living in the next territories. Spawning is preceded with rough courtship games during which fishes chase each other and fish, playing a part of male, pushes the female by side. Female lays eggs in hole on reef surface, preliminary prepared by male. In clutch there are about 200 large eggs strongly inflating in water. Only male cares of posterity. For the period of egg incubation it stops to care of fishes, gets camouflage colouring and almost permanently stays near the nest, fanning eggs by fins and driving away small predators. The incubation lasts about 40 hours, and 3 days after the posterity starts to swim and leaves nest. Young fishes become sexually mature at the age of 1 year.

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