mouth of cat fish, lake fish

A large number of species of catfishes have been named from complete or partial skeletal fossils or even from only otoliths. 19 valid genera and 72 species are based exclusively on fossil remains. There are two fossil families, Andinichthyidae, from the Lower Maastrichtian to Paleocene, as well as Hypsidoridae, from the Middle Eocene.

The earliest known catfish are known from the late Campanian-early Maastrichtian of Argentina. Catfish fossils are known from every continent except Australia. Fossils of the Eocene period have been found from Seymour Island in Antarctica. The order dispersed early throughout the continents primarily through land bridges. Australian species of catfish are all species from families that can enter saltwater; these fish traveled to Australia through saltwater, and then reverted to a freshwater lifestyle.