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 whale shark (Rhincodon typus) is a slow-moving, filter-feedingcarpet shark and the largest known extantfishspecies. An individual with a length of 18.8m (61.7ft) has been considered the largest reliably recorded. The whale shark holds many records for size in the animal kingdom, most notably being by far the largest living non-cetacean animal. It is the only living species of the genus Rhincodon and the only extant member of the family Rhincodontidae, which belongs to the subclass Elasmobranchii in the class Chondrichthyes. Before 1984, it was classified as Rhiniodon into Rhinodontidae. An extinct species, Rhincodon ferriolensis, was described in Europe (probably in Spain), in the Late Burdigalian stage.
The whale shark is an active filter feeder, primarily consuming plankton, krill, fish eggs, and small schooling fish such as sardines and anchovies. The shark can process over 6,000 liters of water per hour through its specialized sieve-like gill pads. Highly migratory, the whale shark travels thousands of miles across tropical oceans to exploit seasonal food sources, with large, predictable feeding aggregations occurring at coastal sites such as Ningaloo Reef in Western Australia, the Yucatan Peninsula in Mexico, and off the coast of Gujarat and Kerala in India. Despite its immense size, the whale shark is docile and poses no significant threat to humans. It is currently listed as an Endangered species on the IUCN Red List owing to a population decline of more than 50% over the last 75 years, primarily as a result of targeted fishing, bycatch in other fisheries, and collisions with large ships. (Full article...)
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The mangrove whipray (Urogymnus granulatus) or whitetail stingray, is a species of stingray in the familyDasyatidae. It is widely distributed in the Indo-Pacific region from the Red Sea to northern Australia and Micronesia. A benthic inhabitant of shallow inshore waters, juvenile mangrove whiprays favor mangrove and estuarinehabitats, while adults favor sandy to rocky areas in lagoons and coral reefs. This species can be identified by its thick, oval pectoral fin disc that is dark gray above with numerous white flecks, and by its relatively short, whip-like tail that is white past the stinging spine. It grows up to 1.4m (4.6ft) across.
The hardnose shark (Carcharhinus macloti) is a species of requiem shark, in the family Carcharhinidae, so named because of the heavily calcifiedcartilages in its snout. A small bronze-coloured shark reaching a length of 1.1m (3.6ft), it has a slender body and a long, pointed snout. Its two modestly sized dorsal fins have distinctively elongated rear tips. The hardnose shark is widely distributed in the western Indo-Pacific, from Kenya to southern China and northern Australia. It inhabits warm, shallow waters close to shore.
The tiger shark (Galeocerdo cuvier) is a species of ground shark, and the only extant member of the genus Galeocerdo and family Galeocerdonidae. It is a large predator, with females capable of attaining a length of over 5m (16ft 5in). Populations are found in many tropical and temperate waters, especially around central Pacific islands. Its name derives from the dark stripes down its body, which resemble a tiger's pattern and fade as the shark matures.
The tiger shark is a solitary, mostly nocturnal hunter. It is notable for having the widest food spectrum of all sharks, with a range of prey that includes crustaceans, fish, seals, birds, squid, octopuses, sea turtles, sea snakes, dolphins, and even smaller sharks. It also has a reputation as a "garbage eater", consuming a variety of inedible, man-made objects that linger in its stomach. Tiger sharks have only one recorded natural predator, the orca. It is considered a near-threatened species because of finning and fishing by humans. (Full article...)
Sturgeon are the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early Jurassic period, some 174 to 201 million years ago. They are one of two living families of the Acipenseriformes alongside paddlefish (Polyodontidae). Sturgeons are native to subtropical, temperate and sub-Arctic rivers, lakes and coastlines of Eurasia and North America. Sturgeons are long-lived, late-maturing fishes with distinctive characteristics, such as a heterocercal caudal fin similar to those of sharks, and an elongated, spindle-like body that is smooth-skinned, scaleless, and armored with five lateral rows of bony plates called scutes.
The grey reef shark or gray reef shark (Carcharhinus amblyrhynchos, sometimes misspelled amblyrhynchus or amblyrhinchos) is a species of requiem shark, in the family Carcharhinidae. One of the most common reef sharks in the Indo-Pacific, it is found as far east as Easter Island and as far west as South Africa. This species is most often seen in shallow water near the drop-offs of coral reefs. It has the typical "reef shark" shape, with a broad, round snout and large eyes. It can be distinguished from similar species by the plain or white-tipped first dorsal fin, the dark tips on the other fins, the broad, black rear margin on the tail fin, and the lack of a ridge between the dorsal fins. Most individuals are less than 1.88m (6.2ft) long.
The grey reef shark is a fast-swimming, agile predator that feeds primarily on free-swimming bony fishes and cephalopods. Its aggressive demeanor enables it to dominate many other shark species on the reef, despite its moderate size. Many grey reef sharks have a home range on a specific area of the reef, to which they continually return. However, they are social rather than territorial. During the day, these sharks often form groups of five to 20 individuals near coral reef drop-offs, splitting up in the evening as the sharks begin to hunt. Adult females also form groups in very shallow water, where the higher water temperature may accelerate their growth or that of their unborn young. Like other members of its family, the grey reef shark is viviparous, meaning the mother nourishes her embryos through a placental connection. Litters of one to six pups are born every other year. (Full article...)
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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The Devils Hole pupfish (Cyprinodon diabolis) is a critically endangered species of the family Cyprinodontidae (pupfishes) found only in Devils Hole, a water-filled cavern in the US state of Nevada. It was first described as a species in 1930 and is most closely related to C. nevadensis and the Death Valley pupfish (C. salinus). The age of the species is unknown, with differing analyses offering ranges between one thousand and sixty thousand years. It is a small fish, with maximum lengths of up to 30mm (1.2in). Individuals vary in coloration based on age and sex: males are bright metallic blue while females and juveniles are more yellow. A defining trait of this species is its lack of pelvic fins. The pupfish consumes nearly every available food resource at Devils Hole, including beetles, snails, algae, and freshwater crustaceans, with diet varying throughout the year. It is preyed on by the predaceous diving beetle species Neoclypeodytes cinctellus, which was first observed in Devils Hole in 1999 or 2000. Reproduction occurs year-round, with spikes in the spring and fall. Females produce few eggs and the survivorship from egg to adult is low. Individuals live 10–14 months.
Devils Hole is more than 130m (430ft) deep, though pupfish are only found in the upper 24m (80ft). The water is a constant temperature of 33°C (91°F) and dissolved oxygen levels are low. A small, shallowly submerged rock shelf provides critical feeding and spawning habitat for the pupfish. Nearby agricultural irrigation in the 1960s and 1970s caused the water to drop in Devils Hole, resulting in less and less of the shelf remaining submerged. Several court cases ensued, resulting in the Supreme Court case Cappaert v. United States, which determined that the preservation of Devils Hole as a National Monument in 1952 implicitly included preservation of adequate groundwater to maintain the scientific value of the pool and its fauna. Other threats faced by the species include flash floods, earthquakes, and vandalism. (Full article...)
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The smoothtooth blacktip shark (Carcharhinus leiodon) is a species of requiem shark in the family Carcharhinidae. It is known only from the type specimen caught from the Gulf of Aden, off eastern Yemen, and a handful of additional specimens caught from the Persian Gulf, off Kuwait. Reaching 1.3m (4.3ft) in length, this species has a stocky greenish-colored body, a short snout, and black-tipped fins. It can be distinguished from similar species by its teeth, which are narrow, erect, and smooth-edged.
Little is known of the smoothtooth blacktip shark's natural history; it likely inhabits shallow waters and feeds on small bony fishes. It is presumably viviparous like other members of its family. The International Union for Conservation of Nature last assessed this species as endangered. Although more specimens have since been discovered, the conservation status of this species remains precarious due to heavy fishing and habitat degradation within its range. (Full article...)
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The common thresher (Alopias vulpinus), also known as Atlantic thresher, is the largest species of thresher shark, family Alopiidae, reaching 6m (20ft) in length. About half of its length consists of the elongated upper lobe of its caudal fin. With a streamlined body, short pointed snout, and modestly sized eyes, the common thresher resembles the pelagic thresher (A. pelagicus). It can be distinguished from the latter species by the white of its belly extending in a band over the bases of its pectoral fins. The common thresher is distributed worldwide in tropical and temperate waters, though it prefers cooler temperatures. It can be found both close to shore and in the open ocean, from the surface to a depth of 550m (1,800ft). It is seasonally migratory and spends summers at lower latitudes.
The long tail of the common thresher, the source of many fanciful tales through history, is used in a whip-like fashion to deliver incapacitating blows to its prey. This species feeds mainly on small schoolingforage fishes such as herrings and anchovies. It is a fast, strong swimmer that has been known to leap clear of the water, and possesses physiological adaptations that allow it to maintain an internal body temperature warmer than that of the surrounding sea water. The common thresher has an aplacental viviparous mode of reproduction, with oophagousembryos that feed on undeveloped eggs ovulated by their mother. Females typically give birth to four pups at a time, following a gestation period of nine months. (Full article...)
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Smalltooth sand tiger in captivity
The smalltooth sand tiger or bumpytail ragged-tooth (Odontaspis ferox) is a species of mackerel shark in the family Odontaspididae, with a patchy but worldwide distribution in tropical and warm temperate waters. They usually inhabit deepwater rocky habitats, though they are occasionally encountered in shallow water, and have been known to return to the same location year after year. This rare species is often mistaken for the much more common sand tiger shark (Carcharias taurus), from which it can be distinguished by its first dorsal fin, which is larger than the second and placed further forward. It grows to at least 5.2m (17ft) in length. They have also been recently sighted in Irish and English waters.
Very little is known of the biology and behavior of the smalltooth sand tiger. It is an active predator of invertebrates, cartilaginous fishes, and bony fishes from the benthic zone. This species is thought to be ovoviviparous with oophagous embryos like other mackerel sharks. In contrast to its formidable size and appearance, this shark is harmless, having never been known to behave aggressively towards humans. Concern exists that its numbers are declining due to human activities in the Mediterranean and elsewhere, though existing data are inadequate for a full assessment of its conservation status. (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...)
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Kuhl's maskray (Neotrygon kuhlii), also known as the blue-spotted stingray, blue-spotted maskray, or Kuhl's stingray, is a species of stingray of the family Dasyatidae. Originally classified in the genus Dasyatis, it was transferred to the genus Neotrygon in 2008 after morphological and molecular analyses showed it to be distinct. The body is rhomboidal and colored green with blue spots. Maximum disk width is estimated 46.5cm (18.3in). It is popular in aquaria, but usually not distinguished from the blue-spotted ribbontail ray. The ribbontail has a rounded body, is a brighter green with brighter blue and more vivid spots, but Kuhl's maskray is larger. The stingray's lifespan is estimated at 13 years for females and 10 years for males. The blue-spotted stingray preys on many fish and small mollusks. It is also generally found from Indonesia to Japan, and most of Australia. Kuhl's maskray also is targeted by many parasites, such as tapeworms, flatworms, and flukes. (Full article...)
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The pigeye shark or Java shark (Carcharhinus amboinensis) is an uncommon species of requiem shark, in the family Carcharhinidae, found in the warm coastal waters of the eastern Atlantic and western Indo-Pacific. It prefers shallow, murky environments with soft bottoms, and tends to roam within a fairly localized area. With its bulky grey body, small eyes, and short, blunt snout, the pigeye shark looks almost identical to (and is often confused with) the better-known bull shark (C. leucas). The two species differ in vertebral count, the relative sizes of the dorsal fins, and other subtle traits. This shark typically reaches lengths of 1.9–2.5m (6.2–8.2ft).
The pigeye shark is an apex predator that mostly hunts low in the water column. It has a varied diet, consisting mainly of bony and cartilaginous fishes and also including crustaceans, molluscs, sea snakes, and cetaceans. This species gives birth to live young, with the developing embryos sustained to term via a placental connection to their mother. Litters of three to thirteen pups are born after a gestation period of nine or twelve months. Young sharks spend their first few years of life in sheltered inshore habitats such as bays, where their movements follow tidal and seasonal patterns. The pigeye shark's size and dentition make it potentially dangerous, though it has not been known to attack humans. The shark is infrequently caught in shark nets protecting beaches and by fisheries, which use it for meat and fins. The IUCN presently assesses this species as vulnerable. (Full article...)
The Murray cod (Maccullochella peelii) is a large Australian predatory freshwater fish of the genus Maccullochella in the family Percichthyidae. Although the species is called a cod in the vernacular, it is not related to the Northern Hemisphere marine cod (Gadus) species. The Murray cod is an important part of Australia's vertebrate wildlife—as an apex predator in the Murray-Darling River system—and also significant in Australia's human culture. The Murray cod is the largest exclusively freshwater fish in Australia, and one of the largest in the world. Other common names for Murray cod include cod, greenfish, goodoo, Mary River cod, Murray perch, ponde, pondi and Queensland freshwater cod.
The scientific name of Murray cod derives from an early Australian fish researcher Allan Riverstone McCulloch and the river from which the explorer Major Mitchell first scientifically described the species, the Peel River. This was for a number of years changed to M. peelii peelii to differentiate Murray cod from Mary River cod, which were designated as a subspecies of Murray cod. However, as of 2010, Mary River cod have been raised to full species status (M. mariensis), thus Murray cod have reverted simply to M. peelii. (Full article...)
Image 4The 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 5Surgeonfish are among the most common of coral reef herbivores, often feeding in shoals. This may be a mechanism for overwhelming the highly aggressive defence responses of small territorial damselfishes that vigorously guard small patches of algae on coral reefs. (from Coral reef fish)
Image 7Young, 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 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 9Scale diagram of the layers of the pelagic zone (from Deep-sea fish)
Image 10The 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 16Humans seldom encounter frilled sharks alive, so they pose little danger (though scientists have accidentally cut themselves examining their teeth). (from Deep-sea fish)
Image 20Most 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 21World distribution of plankton (from Coastal fish)
Image 22In the foreground is an orange-lined triggerfish displaying spines. Triggerfish have mouths that crush shells. Orange-lined triggerfish are particularly aggressive. The black and white fish are three-stripe damselfish and the unstriped fish are blue-green chromis damselfish. If the triggerfish attacks, the damselfish will hide in the nearby cauliflower coral. If the triggerfish wants to hide, it will squeeze into a coral crevice and lock itself in place with its spines. (from Coral reef fish)
Image 31Most mesopelagic fishes are small filter feeders that ascend at night to feed in the nutrient rich waters of the epipelagic zone. During the day, they return to the dark, cold, oxygen-deficient waters of the mesopelagic where they are relatively safe from predators. Lanternfish account for as much as 65% of all deep sea fish biomass and are largely responsible for the deep scattering layer of the world's oceans. (from Pelagic fish)
Image 32Herring reflectors are nearly vertical for camouflage from the side. (from Pelagic fish)
Image 33Coral 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)
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The global continental shelf, highlighted in light blue
Image 39Scale diagram of the layers of the pelagic zone (from Pelagic fish)
Image 40Bigeye tuna cruise the epipelagic zone at night and the mesopelagic zone during the day (from Deep-sea fish)
Image 41Cod-like fishes, like this morid cod have a barbel (fleshy filament) on their lower jaw which they use to detect prey buried in the sand or mud. (from Coastal fish)
Image 48The 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 49Many bristlemouth species, such as the "spark anglemouth" above, are also bathypelagic ambush predators that can swallow prey larger than themselves. They are among the most abundant of all vertebrate families. (from Pelagic fish)
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.
The Eurasian ruffe (Gymnocephalus cernua) is a species of freshwater fish found in temperate regions of Europe and Asia. The aggressive fish is known to reproduce rapidly, leading to problems when it is introduced to foreign bodies of water.
A sketch of a longnose sawshark (Pristiophorus cirratus), a species of sawshark found in the eastern Indian Ocean around southern Australia on the continental shelf at depths of between 40 and 310m (130 and 1,020ft). It is a medium-sized shark with a saw-like flattened snout which measures up to thirty percent of its body size.
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.
In American English, the name gar (or garpike) is strictly applied to members of the Lepisosteidae, a family including seven living species of fish in two genera that inhabit fresh, brackish, and occasionally marine, waters of eastern North America, Central America, and the Caribbean islands.
Bryaninops yongei is a benthic species of goby widely distributed throughout the tropical and subtropical waters of the Indian Ocean; it is commonly found living in and around coral. Although this species was discovered in 1906, its ability to propel itself quickly to escape predators makes it difficult to study.
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 orbicular batfish (Platax orbicularis) is a batfish endemic to the Indian and Pacific Oceans. It has a thin, disc-shaped body, and male can grow up to 50 centimetres (20in) in length. In the wild, the orbicular batfish lives in brackish or marine waters, usually around reefs, at depths from 5 to 30 metres (20 to 100ft). It is also a popular aquarium fish, although captive specimens generally do not grow as long as wild ones.
An Atlantic salmon (Salmo salar) egg hatching. The Alevin (larva) has grown around the remains of the yolk sac - visible are the arteries spinning around the yolk and little oildrops, also the gut, the spine, the main caudalblood vessel, the bladder and the arcs of the gills. In about 24 hours it will be a fry without yolk sac.
The Atlantic spadefish is a species of marine fish endemic to the shallow waters off the coast of the southeastern United States and in the Caribbean Sea. They are similar in appearance to fresh waterangelfish, but much larger, reaching up to three feet (0.9 m) in length. Due to their reputation as strong fighters, they are popular game fish, especially during the summer months when they are most active.
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 leopard shark (Triakis semifasciata) is a species of hound shark found along the Pacific coast of North America from the U.S. state of Oregon to Mazatlán in Mexico. Typically measuring 1.2–1.5 m (3.9–4.9 ft) long, this slender-bodied shark is characterized by black saddle-like markings and large spots over its back.
The mandarinfish (Synchiropus splendidus, not to be confused with the similarly named mandarin fish) is a small (~6cm or 2.4in), brightly-colored member of the dragonet family, popular in the saltwater aquarium trade. The mandarinfish is native to the Western Pacific, ranging approximately from the Ryukyu Islands south to Australia.
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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