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.
Airbreathing catfish comprise the family Clariidae of the order Siluriformes. Sixteen genera and about 117 species of clariid fishes are described; all are freshwater species. Other groups of catfish also breathe air, such as the Callichthyidae and Loricariidae.
The Ictaluridae, sometimes called ictalurids, are a family of catfish native to North America, where they are an important food source and sometimes fished for sport. The family includes about 51 species, some commonly known as bullheads, madtoms, channel catfish, and blue catfish.
The eeltail catfish are a family (Plotosidae) of catfish whose tails are elongated in an eel-like fashion. These catfishes are native to the Indian Ocean and western Pacific from Japan to Australia and Fiji. The family includes about 41 species in 10 genera. About half of the species are freshwater, occurring in Australia and New Guinea.
Clarias is a genus of catfishes of the family Clariidae, the airbreathing catfishes. The name is derived from the Greek chlaros, which means lively, in reference to the ability of the fish to live for a long time out of water.
The Pimelodidae, commonly known as the long-whiskered catfishes, are a family of catfishes.
Glyptothorax is a genus of catfishes order Siluriformes of the family Sisoridae. It is the most species-rich and widely distributed genus in the family with new species being discovered on a regular basis. These species are distributed in the Black Sea basin, northern Turkey, south and east to the Yangtze River drainage in China and south throughout Indo-China to Java, Indonesia. They are found in Asia Minor and southwards to Southeast Asia. The genus is very diverse in the Indian subcontinent. Southeast Asian species tend to have restricted distributions.
Akysis is the largest genus of catfishes of the family Akysidae.
Hemiancistrus is a genus of suckermouth armored catfishes. These species are native to South America. The taxonomy of this genus is complex and unclear, and major work has to be done. Many of these fish are popular aquarium fish.
Horabagrus is a genus of catfish in the family Horabagridae endemic to rivers in the Western Ghats in Kerala and Karnataka, India. H. brachysoma is an important food fish and members of this genus can be found in the aquarium trade.
Pterosturisoma microps is the only species of the monotypic genus Pterosturisoma, a genus of the family Loricariidae of catfish.
Batasio is a genus of catfish of the family Bagridae. These small fish are found in fast-flowing hillstreams throughout South and mainland Southeast Asia.
Hypophthalmus is a genus of long-whiskered catfishes native to freshwater in tropical and subtropical South America.
Mystus is a genus of fish in the family Bagridae native to Asia. Phylogenetic relationships within this genus are poorly understood, though it has been suggested that there are two major lineages.
Pseudobagrus is a genus of bagrid catfishes that inhabit streams and rivers throughout East Asia. About half of these species occur in China.
Neoplecostomus is a genus of fish in the family Loricariidae native to South America. Neoplecostomus can be distinguished from all other loricariids by a modified shield of small plates on the abdomen with posteriorly directed odontodes; the shield appears to act as a holdfast. The color pattern is generally mottled brown with the abdomen white. The head is long, rounded, and shovel-shaped. The fin spines are weak. They range from about 8 to 11 cm (3.1–4.3 in) SL. The species of Neoplecostomus live in fast-flowing water.
Pseudobagarius is a genus of catfishes of the family Akysidae.
Chiloglanis is a genus of upside-down catfishes native to Africa. These species have modified lips and barbels that form a suckermouth. They also have a naked (scaleless) body. Sexual dimorphism has been reported in Chiloglanis. The adult males of many of these species have elongate anal and caudal fins. Also, males may have an enlarged humeral process.
Heteropneustes microps is a species of airsac catfish possibly endemic to Sri Lanka, though records from India have been made. This species grows to a total length of 15.0 cm (5.9 in). This fish is a component of local commercial fisheries, and is found in the aquarium trade.
The Asian stinging catfish or fossil cat is a species of airsac catfish found in India, Bangladesh, Pakistan, Nepal, Sri Lanka, Thailand, Myanmar, and Bhutan. It has also been introduced to the Tigris River Basin in Iran.
