Teleostei, members of which are known as teleosts, is by far the largest infraclass in the class Actinopterygii, the ray-finned fishes, containing 96% of all extant species of fish. Teleosts are arranged into about 40 orders and 448 families. Over 26,000 species have been described.

What makes a fish a teleost?

Teleosts are distinguished primarily by the presence of a homocercal tail, a tail in which the upper and lower halves are about equal. The teleosts comprise some 30,000 species (about equal to all other vertebrate groups combined), with new species being discovered each year.

Is Trout a teleost?

Teleosts including the brown trout and the scaly osman are found in mountain lakes in Kashmir at altitudes as high as 3,819 m (12,530 ft).