Fish Facts » Catfish
Description
Catfish (order Siluriformes) are a very diverse group of bony fish. Named for their prominent barbels, which resemble a cat's whiskers (though not prominent in all members of this order), catfish range in size and behavior from the heaviest, the Mekong giant catfish from Southeast Asia and the longest, the wels catfish of Eurasia, to detritivores (species that eat dead material on the bottom), and even to a tiny parasitic species commonly called the candiru, Vandellia cirrhosa. There are armour-plated types and also naked types, neither having scales. Despite their common name, not all catfish have prominent barbels; what defines a fish as being in the order Siluriformes are in fact certain 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.
Range
Extant catfish species live in inland or coastal waters of every continent except Antarctica. Catfish have inhabited all continents at one time or another. Catfish are most diverse in tropical South America, Africa, and Asia. More than half of all catfish species live in the Americas. They are the only ostariophysans that have entered freshwater habitats in Madagascar, Australia, and New Guinea. They are found primarily in freshwater environments of all kinds, though most inhabit shallow, running water habitats. Representatives of at least eight families are hypogean (live underground) with three families that are also troglobitic (inhabiting caves). Thus, catfishes are some of the most successful cave colonizers among fishes. One such species is Phreatobius cisternarum, known to live underground in phreatic habitats. Numerous species from the families Ariidae and Plotosidae, and a few species from among the Aspredinidae and Bagridae, are also found in marine environments.
Source(s)
Wikipedia
Source(s) on the web
http://en.wikipedia.org/wiki/Catfish