A fish is an aquatic, anamniotic, gill-bearing vertebrateanimal with a tough cranium to protect the brain, but lacking limbs with digits. Fish can be grouped into the more basaljawless fish and the more common jawed fish, the latter including all livingcartilaginous and bony fish, as well as the extinct placoderms and acanthodians. Tetrapods are descended from fish, so in a break from the long tradition of grouping all fish into a single class (Pisces), modern phylogenetics views fish as a paraphyletic group that includes all vertebrates except tetrapods. To treat fish as a monophyletic group, one would have to classify tetrapods as a clade/subgroup of specialized fish, which would make "fish" and "vertebrates" synonyms. In English, the plural of "fish" is fish when referring to individuals and fishes when referring to species.
The goblin shark (Mitsukurina owstoni) is a rare species of deep-sea shark. Sometimes called a "living fossil", it is the only extant representative of the familyMitsukurinidae, a lineage some 125 million years old. This pink-skinned animal has a distinctive profile with an elongated, flat snout, and highly protrusible jaws containing prominent nail-like teeth. It typically reaches a length of 3 to 4 meters (10 to 13 feet) when fully grown, although it can grow significantly larger—such as one specimen captured in 2000, which was believed to measure around 6 meters (20 feet). Goblin sharks are benthopelagic creatures that inhabit upper continental slopes, submarine canyons, and seamounts throughout the world at depths greater than 100m (330ft), with adults found deeper than juveniles. Some researchers believed that these sharks could also dive to depths of up to 1,300m (4,270ft), for short periods; footage captured in 2024 suggests that their range could be deeper than previously thought, with a confirmed sighting of an adult swimming at 2,000m (6,560ft).
Stephanolepis cirrhifer, commonly known as the thread-sail filefish, is a species of marine fish in the family Monacanthidae. It is found in the western Pacific, in an area that ranges from northern Japan to the East China Sea, to Korea. The fish grows to a maximum length of about 12 inches (30 centimetres), and consumes both plant material and small marine organisms like skeleton shrimp. S.cirrhifer is host of the parasitePeniculus minuticaudae. Some minor genetic differentiation between S.cirrhifer born in the wild and those bred in a hatchery for consumer use has been shown. The fish is edible and sold commercially for culinary purposes in many Asian countries. (Full article...)
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The yellowtail flounder (Limanda ferruginea), also known as the rusty dab, is a species of flatfish in the family Pleuronectidae (righteye flounders). Reaching 56cm (22in) in length, it has reddish brown upperparts, pale underparts and yellow fins. Both its eyes are on the right (upper) side of its body. Found in the western North Atlantic, it has been fished commercially by North American fisheries for food. A victim of overfishing, the yellowtail flounder is categorized as "Vulnerable" by the International Union for Conservation of Nature. (Full article...)
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The smalltail shark (Carcharhinus porosus) is a species of requiem shark, and part of the family Carcharhinidae. It is found in the western Atlantic Ocean, from the northern Gulf of Mexico to southern Brazil. It inhabits shallow waters close to shore, particularly over muddy bottoms around estuaries. It tends to swim low in the water column and forms large aggregations segregated by sex. A slim species generally not exceeding 1.1m (3.6ft) in length, the smalltail shark has a rather long, pointed snout, a broad, triangular first dorsal fin, and a second dorsal fin that originates over the midpoint of the anal fin base. It is plain gray in color, without prominent markings on its fins.
Teleostei (/ˌtɛliˈɒstiaɪ/; fromAncient Greekτέλειος (téleios)'complete'andὀστέον (ostéon)'bone'), members of which are known as teleosts (/ˈtɛliɒsts,ˈtiːli-/), is, by far, the largest group of ray-finned fishes (class Actinopterygii), with 96% of all extant species of fish. The Teleostei, which is variously considered a division or an infraclass in different taxonomic systems, include over 26,000 species that are arranged in about 40 orders and 448 families. Teleosts range from giant oarfish measuring 7.6m (25ft) or more, and ocean sunfish weighing over 2t (2.0 long tons; 2.2 short tons), to the minute male anglerfishPhotocorynus spiniceps, just 6.2mm (0.24in) long. Including not only torpedo-shaped fish built for speed, teleosts can be flattened vertically or horizontally, be elongated cylinders or take specialised shapes as in anglerfish and seahorses.
The difference between teleosts and other bony fish lies mainly in their jaw bones; teleosts have a movable premaxilla and corresponding modifications in the jaw musculature which make it possible for them to protrude their jaws outwards from the mouth. This is of great advantage, enabling them to grab prey and draw it into the mouth. In more derived teleosts, the enlarged premaxilla is the main tooth-bearing bone, and the maxilla, which is attached to the lower jaw, acts as a lever, pushing and pulling the premaxilla as the mouth is opened and closed. Other bones further back in the mouth serve to grind and swallow food. Another difference is that the upper and lower lobes of the tail (caudal) fin are about equal in size. The spine ends at the caudal peduncle, distinguishing this group from other fish in which the spine extends into the upper lobe of the tail fin. (Full article...)
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The pyjama shark or striped catshark (Poroderma africanum) is a species of catshark, and part of the familyScyliorhinidae, endemic to the coastal waters of South Africa. This abundant, bottom-dwelling species can be found from the intertidal zone to a depth of around 100m (330ft), particularly over rocky reefs and kelp beds. With a series of thick, parallel, dark stripes running along its stout body, the pyjama shark has an unmistakable appearance. It is additionally characterized by a short head and snout with a pair of slender barbels that do not reach the mouth, and two dorsal fins that are placed far back on the body. It can grow up to a length of 1.1m (3.6ft) long.
The pyjama shark is primarily nocturnal, spending most of the day lying motionless and hidden in a cave or crevice or among vegetation. It often forms groups, particularly during summer. This species is an opportunistic predator that feeds on a wide variety of fishes and invertebrates; it favors cephalopods and frequents the spawning grounds of the chokka squid (Loligo reynaudi). When threatened, it curls into a circle with its tail covering its head. Reproduction is oviparous, with females laying rectangular, dark brown egg cases two at a time year-round. This small and harmless shark adapts well to captivity and is commonly displayed in public aquariums. It is often caught as a bycatch of commercial and recreational fisheries. Many are killed by fishers who regard them as pests. However, there is no data suggesting its numbers have declined, so the International Union for Conservation of Nature (IUCN) has assessed the pyjama shark as least concern. (Full article...)
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A freshwater male
Poecilia vandepolli, or Van de Poll's molly, is a poeciliid fish native to the Caribbean islands of Aruba, Bonaire, and Curaçao. It is one of the most common fish in its range, inhabiting fresh, brackish, salt, and hypersaline waters such as streams, ponds, bays, salt pans, and lagoons. For much of the twentieth century, it was regarded as a subspecies or synonym of P.sphenops, but morphological and genetic studies have confirmed its status as a distinct species. This molly is highly variable in size and color, with males ranging from 2.6 to 5.3cm (1.0 to 2.1in) and females from 3.2 to 9.6cm (1.3 to 3.8in), and coloration varying from grayish-brown to yellow or orange in any given population. Marine fish are generally larger, stronger, and more colorful than freshwater specimens. Males' ability to develop an intense orange coloration may make the species attractive to aquarists.
Forming shoals near the surface, mollies feed mainly on algae, detritus, and aquatic invertebrates, and are preyed upon by other fish and birds. Females produce live fry, giving the species an edge over killifish, with which it competes across its range. Successful reproduction depends on the availability of shelter for fry, most of which fall prey to adults. The species is drawn to freshwater habitats, which disappear in each dry season, killing freshwater populations; these habitats are recolonized from the sea when the rains return. (Full article...)
The body of an alligator gar is torpedo-shaped, usually brown or olive colored, fading to a lighter gray or yellow ventral surface. In very rare occurrences, they can also be black, seen in gars that have a high level of melanin. Their scales are not like the scales of other fishes; rather, they are ganoid scales, which are bone-like, rhomboidal-shaped scales, often with serrated edges, and covered by an enamel-like substance. Ganoid scales are nearly impenetrable, and are excellent protection against predation. Unlike other gar species, the upper jaw of an alligator gar has a dual row of large, sharp teeth that are used to impale and hold prey. Alligator gar are stalking, ambush predators, primarily piscivores, but they also ambush and eat waterfowl and small mammals they find floating on the water's surface. (Full article...)
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The Pacific blue-eye (Pseudomugil signifer) is a species of fish in the subfamilyPseudomugilinae native to eastern Australia. Described by Austrian naturalist Rudolf Kner in 1866, it comprises two subspecies that have been regarded as separate species in the past and may be once again with further study. It is a common fish of rivers and estuaries along the eastern seaboard from Cape York in North Queensland to southern New South Wales, the Burdekin Gap in central-north Queensland dividing the ranges of the two subspecies.
A small silvery fish averaging around 3.25 cm in total length (1+1⁄8–1+3⁄8 in), the Pacific blue-eye is recognisable by its blue eye-ring and two dorsal fins. It forms loose schools of tens to thousands of individuals. It eats water-borne insects as well as flying insects that land on the water's surface, foraging for them by sight. The Pacific blue-eye adapts readily to captivity. (Full article...)
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The estuary stingray (Hemitrygon fluviorum), also called the estuary stingaree or brown stingray, is a species of stingray in the familyDasyatidae. Endemic to eastern Australia, it typically inhabits shallow, mangrove-lined tidal rivers, estuaries, and bays in southern Queensland and New South Wales. This yellow-brown to olive ray grows to at least 93cm (37in) across. It has a diamond-shaped pectoral fin disc and a mostly smooth, whip-like tail bearing both dorsal and ventral fin folds. It can additionally be identified by its long, narrow nostrils and the row of thorns along the midline of its back.
Weighing up to 90kg (200lb), with a length of 1.8m (6ft), the Atlantic torpedo is the largest known electric ray. Like other members of its genus, it has an almost circular pectoral fin disk with a nearly straight leading margin, and a robust tail with a large triangular caudal fin. Distinctive characteristics include its uniform dark color, smooth-rimmed spiracles (paired respiratory openings behind the eyes), and two dorsal fins of unequal size. Its diet consists mainly of bony fish, though it also feeds on small sharks and crustaceans. (Full article...)
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A male (bottom) with females (top)
Poecilia velifera, commonly known as the Yucatán molly or giant sailfin molly, is a poeciliid fish native to the Yucatán Peninsula in Mexico. It is typically under 10cm (3.9in) in length but may reach 15cm (5.9in), with males somewhat larger than females. It belongs to a group of mollies known as sailfins, named for the large males' sail-like dorsal fin, a feature that is especially pronounced in P. velifera. The species occurs in a range of habitats, from coastal lagoons, estuaries, and salt marshes to freshwater pools in the interior of the peninsula; it is particularly associated with mangrove swamps and sinkholes known as cenotes.
Yucatán mollies are primarily herbivorous, but also consume small invertebrates, adjusting their diet to available resources. They are preyed upon by a variety of larger fish, birds, and crocodilians, and are host to a diverse parasite fauna. Much of their time is spent browsing for food and maintaining their bodies. Males are divided into size-based classes, which differ in appearance and behavior: the largest males flare their dorsal fin when they spar with other males and when they perform courtship displays for females; the smallest males remain hidden among females and mate through quick thrusts; and the intermediate males may employ either strategy. A few weeks after mating, females give birth to live young. P. velifera produces viable hybrids with other mollies, including the naturally occurring P. mexicana×P. velifera. (Full article...)
Cretoxyrhina (/krɪˌtɒksiˈrhaɪnə/; meaning 'Cretaceous sharp-nose') is an extinct genus of large mackerel shark that lived about 107 to 73 million years ago during the late Albian to late Campanian of the Late Cretaceous. The type species, C. mantelli, is more commonly referred to as the Ginsu shark, first popularized in reference to the Ginsu knife, as its theoretical feeding mechanism is often compared with the "slicing and dicing" when one uses the knife. Cretoxyrhina is traditionally classified as the likely sole member of the familyCretoxyrhinidae but other taxonomic placements have been proposed, such as within the Alopiidae and Lamnidae.
Measuring up to 8m (26ft) in length and weighing around 5,000kg (11,000lb), Cretoxyrhina was one of the largest sharks of its time. Having a similar appearance and build to the modern great white shark, it was an apex predator in its ecosystem and preyed on a large variety of marine animals including mosasaurs, plesiosaurs, sharks and other large fish, pterosaurs, and occasionally dinosaurs. Its teeth, up to 8cm (3.1in) long, were razor-like and had thick enamel built for stabbing and slicing prey. Cretoxyrhina was also among the fastest-swimming sharks, with hydrodynamic calculations suggesting burst speeds of up to 70km/h (43mph). It has been speculated that Cretoxyrhina hunted by lunging at its prey at high speeds to inflict powerful blows, similar to the great white shark today, and relied on strong eyesight to do so. (Full article...)
Paddlefish are members of the ray-finned fish family Polyodontidae, which belong to the basal order Acipenseriformes, one of two living groups within this order alongside sturgeons (Acipenseridae). Their most distinctive feature is an elongated rostrum that enhances electroreception, allowing them to detect prey in murky water. Both recent and fossil paddlefish occur exclusively in North America and Eastern Asia.
Eight species are known, six of which are prehistoric and only known from fossils—five from North America and one from China. Of the two species to have survived until modern times, the American paddlefish (Polyodon spathula) inhabits the Mississippi River basin in the United States, while the now extinct Chinese paddlefish (Psephurus gladius, also known as the "Chinese swordfish") inhabited the Yangtze and Yellow River basins in China. The earliest known paddlefish fossil, Protopsephurus, dates to approximately 120 million years ago during the Early Cretaceous epoch in China. (Full article...)
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The Sacred Cod in its "natural habitat". "Humble the subject and homely the design; yet this painted image bears on its finny front a majesty greater than the dignity that art can lend to graven gold or chiselled marble", said an 1895 paean by Massachusetts legislators.[C]:12
The Sacred Cod is a four-foot-eleven-inch (150cm) carved-wood effigy of an Atlantic codfish, painted to the life, hanging in the House of Representatives chamber of Boston's Massachusetts State House—"a memorial of the importance of the Cod-Fishery to the welfare of this Commonwealth" (i.e. Massachusetts, of which cod is officially the "historic and continuing symbol"). The Sacred Cod has gone through as many as three incarnations over three centuries: the first (if it really existed—the authoritative source calling it a "prehistoric creature of tradition") was lost in a 1747 fire; the second disappeared during the American Revolution; and the third, installed in 1784, is the one seen in the House chamber today.
"Sacred Cod" is not a formal name but a nickname which appeared in 1895, soon after the carving was termed "the sacred emblem" by a House committee appointed "to investigate the significance of the emblem [which] has kept its place under all administrations, and has looked upon outgoing and incoming legislative assemblies, for more than one hundred years".[C]:3–4, 12 Soon sacred cod was being used in reference to actual codfish as well, in recognition of the creature's role in building Massachusetts's prosperity and influence since early colonial times. (Full article...)
The body of an alligator gar is torpedo-shaped, usually brown or olive colored, fading to a lighter gray or yellow ventral surface. In very rare occurrences, they can also be black, seen in gars that have a high level of melanin. Their scales are not like the scales of other fishes; rather, they are ganoid scales, which are bone-like, rhomboidal-shaped scales, often with serrated edges, and covered by an enamel-like substance. Ganoid scales are nearly impenetrable, and are excellent protection against predation. Unlike other gar species, the upper jaw of an alligator gar has a dual row of large, sharp teeth that are used to impale and hold prey. Alligator gar are stalking, ambush predators, primarily piscivores, but they also ambush and eat waterfowl and small mammals they find floating on the water's surface. (Full article...)
Image 2Most of the rest of the mesopelagic fishes are ambush predators, such as this sabertooth fish. The sabertooth uses its telescopic, upward-pointing eyes to pick out prey silhouetted against the gloom above. Their recurved teeth prevent a captured fish from backing out. (from Pelagic fish)
Image 5Scale diagram of the layers of the pelagic zone (from Deep-sea fish)
Image 6The humpback anglerfish is a bathypelagic ambush predator, which attracts prey with a bioluminescent lure. It can ingest prey larger than itself, which it swallows with an inrush of water when it opens its mouth. (from Pelagic fish)
Image 7Some flatfish can camouflage themselves on the ocean floor (from Demersal fish)
Image 8The stoplight loosejaw is also one of the few fishes that produce red bioluminescence. As most of their prey cannot perceive red light, this allows it to hunt with an essentially invisible beam of light. (from Deep-sea fish)
Image 9Herring reflectors are nearly vertical for camouflage from the side. (from Pelagic fish)
Image 10Bigeye tuna cruise the epipelagic zone at night and the mesopelagic zone during the day (from Deep-sea fish)
Image 13Demersal fish output in 2005 (from Demersal fish)
Image 14The stoplight loosejaw has a lower jaw one-quarter as long as its body. The jaw has no floor and is attached only by a hinge and a modified tongue bone. Large fang-like teeth in the front are followed by many small barbed teeth. (from Deep-sea fish)
Image 16Young, red flabby whalefish make nightly vertical migrations into the lower mesopelagic zone to feed on copepods. When males mature into adults, they develop a massive liver and then their jaws fuse shut. They no longer eat, but continue to metabolise the energy stored in their liver. (from Pelagic fish)
Image 17Coral reefs support flourishing ecosystems, paradoxically in clear, low nutrient waters, along tropical continental coasts and around volcanic islands. Coral reef fish are numerous and diverse. (from Coastal fish)
Image 18The yellow tang, a usually placid surgeon fish, can erect spines in its tail and slash at its opponent with rapid sideways movements. (from Coral reef fish)
Image 19Red snapper, are generalized reef feeders with standard jaw and mouth structures that allow them to eat almost anything, though they prefer small fish and crustaceans. (from Coral reef fish)
Image 25Shortfin mako shark make long seasonal migrations. They appear to follow temperature gradients, and have been recorded travelling more than 4,500 km in one year. (from Pelagic fish)
Image 31The great hammerhead detects the electrical signatures of stingrays buried in the sand and pins them with its "hammer". (from Demersal fish)
Image 32The giant whale shark, another resident of the ocean epipelagic zone, filter feeds on plankton, and periodically dives deep into the mesopelagic zone. (from Pelagic fish)
Image 49Long-snouted lancetfish. Lancetfish are ambush predators which spend all their time in the mesopelagic zone. They are among the largest mesopelagic fishes (up to 2m (6.6ft). (from Deep-sea fish)
Image 50Scale diagram of the layers of the pelagic zone (from Pelagic fish)
Brachysomophis cirrocheilos, the stargazer snake eel, is a marine fish belonging to the family Ophichthidae. It is native to shallow tropical and subtropical waters in the western Indo-Pacific region. It hunts at night for crustaceans and small fish, after which it submerges itself into the sediment tail first and remains there all day, with just its eyes and the top of its head projecting, as seen here in Batangas Bay in the Philippines.
A plate with fossils of Pseudostacus sp. (lobster, left) and Diplomystus birdii (fish, right), from the Hakel paleontological formation in Lebanon. The paleontological sites of Lebanon contain deposits of some of the best-preserved fossils in the world, and include some species found nowhere else. The most famous of these is the Lebanese lagerstätten of the Late Cretaceous age.
A discus (Symphysodon discus) is guarding its eggs. As for most cichlids, brood care is highly developed with both the parents caring for the young. Additionally, adult discus produce a secretion through their skin, off which the larvae live during their first few days.
The Siamese fighting fish (Betta splendens), or fighting betta is a freshwaterfish related to the paradise fish. The fighting fish is a species in the Gourami family which is popular as an aquarium fish. They are called pla-kad (biting fish) in Thai or trey krem in Khmer. They are a very territorial fish and it is unwise to house two males together. Even the females may become territorial towards each other if not housed in a large enough tank.
Mudskippers, such as this Periophthalmodon septemradiatus, are uniquely adapted to a completely amphibious lifestyle. They are active when out of water, feeding and interacting with one another, as well as defending their territories.
The round ribbontail ray (Taeniura meyeni) is a species of stingray in the family Dasyatidae, found throughout the nearshore waters of the tropical Indo-Pacific region. Reaching 1.8m (6ft) across, this large ray is characterized by a thick, rounded pectoral fin disc covered by small tubercles on top, and a relatively short tail bearing a single venomous spine. The ray is well-camouflaged when lying on the seabed; it is largely nocturnal, and preys on molluscs, crustaceans and bony fish. Mature females bear litters of up to seven pups, which are fed during gestation on "uterine milk", a product secreted by the walls of the oviduct. This round ribbontail ray was photographed in Lakshadweep, India.
The flying gurnard is a fish of tropical to warm temperate waters on both sides of the Atlantic Ocean. When excited, it spreads its "wings", semi-transparent appendages tipped with a phosphorescent bright blue coloration which are used to frighten predators.
People jigging—fishing with a type of lure known as a "jig"—for squid in Queenscliff, Victoria, Australia. A jig consists of a lead sinker with a hook molded into it and usually covered by a soft body to attract fish. Jigs are intended to create a jerky, vertical motion, as opposed to spinnerbaits which move through the water horizontally.
Icefish are a type of Antarctic fish belonging to various families, including the Channichthyidae family. They have no haemoglobin and their blood is transparent. They feed on krill, copepods, and other fish. Icefish rely on well-oxygenated water and absorb oxygen directly through the skin as they lack red blood cells.
Koi are ornamental domesticated varieties of the common carpCyprinus carpio, originated from China and widely spread in Japan. They are very closely related to goldfish. The word "koi" comes from Japanese meaning "carp".
Rhinogobius flumineus, also known as the lizard goby, is a species of goby in the family Oxudercidaeendemic to Japan, seen here in Hamamatsu, Shizuoka Prefecture. A small freshwater fish found in fast-flowing streams, it maintains its position against the current by gripping a rock with a sucker formed from two of its fins. The fish's mouth is slightly asymmetric; dextral (right-sided) fish tend to curve their bodies to the right as they rest, while sinistral (left-sided) fish tend to adopt a left-curving posture. The fish are omnivorous, picking edible items off the stream bed with the side of the mouth, but dextral and sinistral fish show no preference for which side of the mouth they use for this purpose.
The giant grouper (Epinephelus lanceolatus), shown here with a school of golden trevally, is the largest bony fish found in coral reefs, and the aquatic emblem of Queensland, Australia. The species can grow as large as 2.7 meters (9ft) long, weighing up to 400 kg (880lb). They are fairly common in shallow waters and feed on a variety of marine life, including small sharks and juvenile sea turtles.
The Peacock flounder (Bothus mancus) is a species of lefteye flounder found widely in relatively shallow waters in the Indo-Pacific. This photomontage shows four separate views of the same fish, each several minutes apart, starting from the top left. Over the course of the photos, the fish changes its colors to match its new surroundings, and then finally (bottom right) buries itself in the sand, leaving only the eyes protruding.
The Mini Edition of the Fish Portal is available for you to use on your wikipedia user page or talk page. It uses minimum space but retains many crucial features of the portal. To use it, place {{Portal:Fish/Mini portal}} on the designated page. See here for an example of the mini portal on a user page.
The Fish Quiz is a friendly quiz competition designed to test your general knowledge of fish. The current game is Fish Quiz Tournament X. You can read more and join the game here.
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