The trout-perch belongs to the family Percopsidae, which includes only one genus—Percopsis—with only two species . The fish is found only in the fresh waters of North America . One species (Percopsis omiscomaycus) is found mainly on the eastern side; the other species, the sandroller (P. Transmontana), is native to the west in the regions around the Columbia River Basin .
Both species are small, with the eastern species averaging 3-5 in (7.6-12.7 cm) in length, with a few reaching 8 in (20.3 cm). The sandroller is a bit smaller.
As the name implies, the trout-perch has characteristics of both the trout and the perch . Like the trout, it has an adipose fin-a fatty fin which projects between the dorsal and caudal fins. It also has a lateral line (a row of sensory pores on its sides) and ctenoid scales (fish scales that have a comb-like projection at their margin).
The trout-perch appears to prefer deep water but may enter shallow water in spring to spawn. It may spawn on sandbars in lakes or up rivers , selecting bottoms of sand or gravel. It appears to be sensitive to rises in temperature , and, in some lakes, a considerable number of these fish die off in the summer as the water temperature rises.
Trout-perches are an important source of food for larger fishes.