North American freshwater catfishes
Gill [T. N.]
A moderate sized family of 7 genera (3 monotypic) and at least 46 species of North American freshwater fishes, plus 2 additional fossil genera and 14 fossil species. Living species range from southern Canada south to extreme southern Mexico, northern Guatemala, and Belize, but it is uncertain whether presence in the last country is natural or results from an early introduction. The native ranges of most living species are confined to Atlantic drainages, but three are native to Pacific drainages of Mexico. Fossil records indicate the family also was once widespread in Pacific slope drainages of the United States and possibly southwestern Canada. The closest family relationship has been hypothesized to be with the morphologically similar old-world family Bagridae, but Lundberg (1992:395 [ref. 23260]) indicates that this relationship has yet to be firmly established. Maximum adult sizes of individual species range from approximately 36 mm and a few ounces to 1600 mm and over 50 kilograms (110-125 pounds). Skin naked; eight barbels on head (two nasal, two maxillary, four chin); adipose fin present, either separate from or narrowly confluent with caudal fin; first five vertebrae behind head fused (Weberian apparatus); dorsal and pectoral fins almost always spinelike (actually comprised of fused soft rays), with poison glands often present at bases (better developed with pectoral spines), which can result in an unpleasant sting following a puncture wound; dorsal fin usually with 6 soft rays; caudal fin forked to rounded; eye small or absent (in subterranean species); mouth large and either terminal or slightly subterminal; palate toothless in all living species; maxilla toothless and rudimentary, but premaxilla with tiny reduced teeth. All species are nocturnal. Habitat variable, ranging from swift, well-oxygenated streams to quiet weedy sloughs and occasionally subterranean situations (last type of habitat includes four species, equally divided between Texas and Mexico). Species are nest builders, with the male excavating the nest and guarding the eggs. They are basically carnivores, and feed on both invertebrates and fish. The larger species are important food and game fishes. Several of the larger species have been widely introduced, which has made determination of their original ranges difficult.
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