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The Catfish

Channel Catfish

Catfish is a common name for about 2200 species of fishes, of which some 1200 are South American. Two families are primarily marine. All other families inhabit fresh water. Catfishes are mostly nocturnal scavengers, living near the bottom in shallow waters.

The name catfish is derived from the feelers, or barbels, that extend from each side of the upper jaw of the fish and, in some species, from the lower jaw also, suggesting the whiskers of a cat. The dorsal and pectoral fins are often edged with sharp spines, in some cases poisonous, which are used in defense and can inflict severe wounds. Members of several catfish families in South America are covered with bony plates. Catfishes vary considerably in size. Small species, such as the dwarf Corydoras, or micro cat (C. hastatus), may be as little as 4 or 5 centimetres (1 1/2-2 inches) long, while the wels or sheatfish(Silurus glanis), a large, European species, may be 4.5 metres (15 feet) in length and 300 kilograms (660 pounds) in weight.

The blind catfish, found in caverns in eastern Pennsylvania, has atrophied eyes, and the electric catfish of the Nile River and tropical central Africa is capable of giving an electric shock (see Electric Fish). Another odd catfish, the so-called walking catfish, originally occurred in eastern India and Southeast Asia. In 1968, it was discovered near Boca Raton, Florida, following its import by tropical-fish dealers. Its maximum length is 56 cm (22 in). In "walking" to areas of deeper water in dry spells, this catfish moves across land (between bodies of water) by a slithering motion combined with a thrashing of its tail. In addition, a stout spine in each pectoral fin digs into the ground to help balance and propel the fish. It is able to breathe air by means of a modified gill arch that forms an air chamber.

Some species of catfish are believed to be among the largest freshwater fish in the world. A specimen of giant catfish, Pangasianodon gigas, netted in 2005 in the Mekong River in northern Thailand, reportedly weighed 293 kg (646 lb) and measured 2.7 m (9 ft) in length.

Of the numerous species of North American catfishes, the bullhead is commonly fished for eating. Of greatest commercial importance are fishes in the Mississippi River valley and the Gulf states, some of which weigh as much as 70 kg (as much as 150 lb). The blue catfish, or chucklehead, and the channel catfish, the flesh of which is esteemed as equal to that of black bass, form the major part of the harvest.

Catfishes currently account for about one-half of the aquaculture production in the United States. Mississippi, Alabama, Arkansas, California, and Louisiana all have extensive catfish farms; there are a total of about 60,700 hectares (about 150,000 acres) of catfish farms in these and other states. The United States production of farm-raised catfishes increased from less than 90 million kg (less than 200 million lb) in 1985 to more than 200 million kg (more than 450 million lb) in 1992, and commercial sales of farmed catfishes were estimated at about 200 million kg (about 450 million lb) in 1993. New technologies such as genetic improvement, recirculating systems, and control of diseases may continue to promote the growth of this industry.

Electric catfish

Electric Catfish

The Electric catfish(Malapterurus electricus) is a widely distributed freshwater catfish native to tropical Africa. The only member of the family Malapteruridae, it is a thickset fish with six mouth barbels and a single fin (the adipose fin) on its back, just anterior to the rounded tail fin. It is brownish or grayish, irregularly spotted with black, and attains a length and weight of about 1.2 metres (4 feet) and 23 kilograms (51 pounds).

The electric catfish is capable of generating and controlling the discharge of up to 450 volts of electricity. It uses its power to defend itself and to capture prey. The electric organ is composed of modified muscle tissue and forms a fine, gelatinous layer directly beneath the soft, naked skin of the fish. The electric catfish is hardy and, though pugnacious, is sometimes kept in home aquariums. It was pictured on tombs by the ancient Egyptians.

"catfish." Encyclopædia Britannica from Encyclopædia Britannica 2007 Ultimate Reference Suite. (2007).