Saturday, May 24, 2008

Catfish

Catfish comprise about 2,000 species of mostly freshwater fishes in the order Silurifrmes. Distributed worldwide, they are most diverse in South America. Catfish are distinguished by the presence of barbells, or whiskers; the lack of true scales; strong spines at the front of the dorsal and pectoral fins; and in most cases, an adipose fin on top of the body is usually partly to completely armored. Most catfish have small eyes, they rely on taste, smell, and hearing. The barbells and much of the skin are often covered with taste buds. Many catfish are inactive during the day, coming out to feed at night. Freshwater catfish usually spend mush of their time (and lay their eggs) in hollow logs, undercut banks, and other hiding places. One or both parents guard the eggs until they hatch. In Indonesian this fish is called "lele".

Many species of fresh water catfish are used for human food. North American catfish of the genus Ictalurus are important commercially and are popular with anglers. Catfish farming involves raising and marketing such species as the channel catfish, I. punctatus.

Some catfish are quite distinctive in appearance or behavior. A parasitic catfish, the candiru, Candellis cirrhosa, a minute South American catfish with strong, recurved spines, has been known to enter the urinary tract of persons wading in the water. The electric catfish Malapterurus electricus, native to Africa, can produce a charge of up to 350 volts, enough to stun a human. The predatory walking catfish, clarias batrachus, has lunglike organs that allow it to breathe air, enabling it to move over land from one body of water to another. A European catfish, the wells, Silurus glanis, is one of the largest freshwater fishes, reaching 4,5 m (15 ft) in length and 300 kg (660 lb) in weight.

Catfish are bottom dwelling fish marked by the presence around the mouth of sensitive tactile organs (barbells) that look like a cat's whiskers.

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