Gymnocephalus is a genus of ray-finned fishes from the family Percidae, which includes the perches, pike-perches and darters. They are from the Western Palearctic area, although one species, Gymnocephalus cernua has been accidentally introduced to the Great Lakes region where it is regarded as an invasive species. They have the common name "ruffe" and resemble the true perches in the genus Perca, but are usually smaller and have a different pattern.

Sander is a genus of predatory ray-finned fish in the family Percidae, which also includes the perches, ruffes, and darters. They are also known as "pike-perch" because of their resemblance to fish in the unrelated Esocidae (pike) family. They are the only genus in the monotypic tribe Luciopercini, which is one of two tribes in the subfamily Luciopercinae.