The Percopsiformes are a small order of ray-finned fishes, comprising the trout-perch and its allies. It contains just ten extant species, grouped into seven genera and three families. Five of these genera are monotypicThey are generally small fish, ranging from 5 to 20 cm (2.0 to 7.9 in) in adult body length. They inhabit freshwater habitats in North America.