The South American catfishes show great diversity: There are small, delicate species armored with bony plates; parasitic types that live in the gills of other fish; and one catfish of the E Andes in which the pelvic fins are modified into suckers that enable it to cling to rocks. African species include the electric fish and the Nile catfish, which swims upside down to feed at the water's surface and has a white back and a dark belly, the reverse of the normal coloration.
Of the 30 American species the largest and most important is the blue, or Mississippi, catfish, an excellent food fish weighing up to 150 lb (70 kg). Best known is the smaller channel catfish, which reaches 20 lb (9 kg) and has a deeply forked tail and slender body. The stonecat, 10 in. (25.4 cm) long, is found in clear water under logs and stones. The bullheads, or horned pouts, are catfish of muddy ponds and streams, feeding on bottom plants and animals. Bullheads have square or slightly rounded tails and may reach 1 ft (30 cm) in length and 2 lb (0.9 kg) in weight. The black, yellow, and brown bullhead species are common in the waters of the central and eastern states.
There are no catfish in the Pacific except the introduced white catfish. Marine catfish found during the summer in bays and harbors of the Atlantic and Gulf states include the 2-ft (61-cm) gaff-topsail catfish, named for its long, ribbonlike pectoral and dorsal fins, and the smaller sea catfish, a very common trash fish. The males of both these species carry the fertilized eggs in their mouths (and therefore do not eat) until well after the young hatch, a period of two months. In certain other species the eggs are embedded in the underside of the female. Some tropical catfish survive dry seasons by burrowing into the mud or by crawling overland in search of water.
The Columbia Electronic Encyclopedia, 6th ed. Copyright © 2012, Columbia University Press. All rights reserved.