The Percopsiformes are a small order of freshwater teleost fishes measuring less than in length, 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 monotypic.
They inhabit freshwater habitats in North America, and fossil evidence indicates that they have inhabited this region since the Late Cretaceous, with both suborders having diverged by the Maastrichtian. Despite their scientific name and the common names for some taxa, they are not closely related to actual perches in the order Perciformes, and rather represent a freshwater lineage of the otherwise almost entirely marine superorder Paracanthopterygii. They are more closely related to the cods, dories, and the deep-sea tube-eye, and fossil evidence suggests that their closest relative was the extinct order Sphenocephaliformes, comprising two enigmatic genera of Late Cretaceous marine fish, as well as Omosomopsis, another Cretaceous marine fish from Morocco.
- Genus †Lateopisciculus <small>Murray & Wilson 1996</small>
- Genus †Percopsiformorum [Otolith]
- Suborder Percopsoidei <small>Berg 1937</small>
- Genus †Lindoeichthys (Late Cretaceous of Canada)