Catfish are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, the Mekong giant catfish from Southeast Asia, the wels catfish of Eurasia, and the piraíba of South America, to detritivores, and even to a tiny parasitic species commonly called the candiru, Vandellia cirrhosa. Neither the armour-plated types nor the naked types have scales. Despite their name, not all catfish have prominent barbels or "whiskers". Members of the Siluriformes order are defined by features of the skull and swimbladder. Catfish are of considerable commercial importance; many of the larger species are farmed or fished for food. Many of the smaller species, particularly the genus Corydoras, are important in the aquarium hobby. Many catfish are nocturnal, but others are crepuscular or diurnal.
Sturgeon is the common name for the 28 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). The family is grouped into four genera: Acipenser, Huso, Scaphirhynchus, and Pseudoscaphirhynchus. Two species may be extinct in the wild, and one may be entirely extinct. Sturgeons are native to subtropical, temperate and sub-Arctic rivers, lakes and coastlines of Eurasia and North America. A Maastrichtian-age fossil found in Morocco shows that they also once lived in Africa.
The Chinese paddlefish, also known as the Chinese swordfish, is an extinct species of fish that was formerly native to the Yangtze and Yellow River basins in China. With records of specimens over three metres and possibly 7 m (23 ft) in length, it was one of the largest species of freshwater fish. It was the only species in the genus Psephurus and one of two recent species of paddlefish (Polyodontidae), the other being the American paddlefish. It was an anadromous species, meaning that it spent part of its adult life at sea, while migrating upriver to spawn.
The iridescent shark,iridescent shark catfish is a species of shark catfish native to the rivers of Southeast Asia. Despite its name, it is not a shark. It is found in the Mekong basin as well as the Chao Phraya River, and is heavily cultivated for food there.
Loricariidae is the largest family of catfish, with 92 genera and just over 680 species. Loricariids originate from freshwater habitats of Costa Rica, Panama, and tropical and subtropical South America. These fish are noted for the bony plates covering their bodies and their suckermouths. Several genera are sold as "plecos", notably the suckermouth catfish, Hypostomus plecostomus, and are popular as aquarium fish.
The zebra oto or tiger oto is a fish of the genus Otocinclus of the family Loricariidae that originates from Peru.
The beluga, also known as the beluga sturgeon or great sturgeon, is a species of anadromous fish in the sturgeon family (Acipenseridae) of the order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and formerly in the Adriatic Sea. Based on maximum size, it is the third-most-massive living species of bony fish. Heavily fished for the female's valuable roe, known as beluga caviar, wild populations have been greatly reduced by overfishing and poaching, leading IUCN to classify the species as critically endangered.
The walking catfish is a species of freshwater airbreathing catfish native to Southeast Asia. It is named for its ability to "walk" and wiggle across dry land, to find food or suitable environments. While it does not truly walk as most bipeds or quadrupeds do, it can use its pectoral fins to keep it upright as it makes a wiggling motion with snakelike movements to traverse land. This fish normally lives in slow-moving and often stagnant waters in ponds, swamps, streams, and rivers, as well as in flooded rice paddies, or temporary pools that may dry up. When this happens, its "walking" skill allows the fish to move to other aquatic environments. Considerable taxonomic confusion surrounds this species and it has frequently been confused with other close relatives. One main distinction between the walking catfish and the native North American ictalurid catfish with which it sometimes is confused, is that the walking catfish lacks an adipose fin. It can survive 18 hours out of water.
The kaluga, also known as the river beluga, is a large predatory sturgeon found in the Amur River basin. With a maximum size of at least 1,000 kg (2,205 lb) and 5.6 m (18.6 ft), the kaluga is one of the biggest of the sturgeon family. Like the slightly larger beluga, it spends part of its life in salt water. Unlike the beluga, this fish has 5 major rows of dermal scutes and feeds on salmon and other fish in the Amur. They have gray-green to black backs with a yellowish green-white underbelly.
The Mekong giant catfish, is a large, threatened species of catfish in the shark catfish family (Pangasiidae), native to the Mekong basin in Southeast Asia and adjacent China. It is considered critically endangered due to overfishing and habitat loss.
The wels catfish, also called sheatfish or just wels, is a large species of catfish native to wide areas of central, southern, and eastern Europe, in the basins of the Baltic, Black and Caspian Seas. It has been introduced to Western Europe as a prized sport fish and is now found from the United Kingdom east to Kazakhstan and China and south to Greece and Turkey. The wels is the largest freshwater fish in Europe. The longest wels on record was an unweighed specimen from the Po river in Italy, measuring 2.85 m (9.4 ft), captured in 2023.
The shovelnose sturgeon is the smallest species of freshwater sturgeon native to North America. It is often called hackleback, sand sturgeon, or switchtail. Switchtail refers to the long filament found on the upper lobe of the caudal fin. Shovelnose sturgeon are the most abundant sturgeon found in the Missouri River and Mississippi River systems, and were formerly a commercially fished sturgeon in the United States of America. In 2010, they were listed as threatened under the U.S. Endangered Species Act due to their resemblance to the endangered pallid sturgeon, with which shovelnose sturgeon are sympatric.
The pallid sturgeon is an endangered species of ray-finned fish, endemic to the waters of the Missouri and lower Mississippi river basins of the United States. It may have even reached the St. Croix River before colonization.
Pterygoplichthys, sometimes collectively known as janitor fish, is a genus of South American armored catfishes. These fish are commonly known as sailfin armoured catfish or sailfin plecs, especially in the aquarium trade.
Hypancistrus is a genus of loricariid catfish originating from the Amazon basin in South America. Unlike many of the other Loricariids, however, some Hypancistrus species are more carnivorous and enjoy meat in their diet. Hypancistrus species are popular aquarium fish, including such popular fish as the zebra pleco and Queen Arabesque pleco.
Harttiella crassicauda is a species of armored catfish.
Dabry's sturgeon, also known as the Yangtze sturgeon, Changjiang sturgeon and river sturgeon, is a species of fish in the sturgeon family, Acipenseridae. It is endemic to China and today restricted to the Yangtze River basin, but was also recorded from the Yellow River basin in the past. It was a food fish of commercial importance. Its populations declined drastically, and since 1988, it was designated an endangered species on the Chinese Red List in Category I and commercial harvest was banned. It has been officially declared extinct in the wild by the IUCN as of July 21, 2022.
The Adriatic sturgeon is a species of fish in the family Acipenseridae. It is native to the Adriatic Sea and large rivers which flow in it of Albania, Greece, Italy, Montenegro, Croatia, Bosnia and Herzegovina and Slovenia. Specimens can be seen in several public aquarium, such the Milan Aquarium, Aquarium Finisterrae, Aquarium of the Po, and Oasis of Sant'Alessio in Lombardy.
Cavefish or cave fish is a generic term for fresh and brackish water fish adapted to life in caves and other underground habitats. Related terms are subterranean fish, troglomorphic fish, troglobitic fish, stygobitic fish, phreatic fish, and hypogean fish.
Synodontis acanthoperca, known as the scissortail synodontis, is a species of upside-down catfish native to Gabon where it occurs in the Ogowe River. It was first described by John Patrick Friel & Thomas R. Vigliotta in 2006, based upon a holotype discovered in the Ogooué River in Gabon, at and below the Rapids of Massoukou. The specific name "acanthoperca" comes from the Latinized combination of the Greek word acantha, meaning "thorn", and the Latin opercul, meaning cover or lid, which refers to the pronounced spines that develop on the operculum of mature males.
