"Perches" is a generic common name given to a large number of fish. Many of them not related. If you want to get scientific though about 40% of all the worlds fishes could be called perches. That's because the order Perciformes (perch-like) is the largest order of vertebrates on the planet. This order includes sunfishes, snooks, cichlids, billfish, snappers, gobies, barracuda, tuna, snakeheads and a ton of other fish families. Within this order though there is the family Percidae and I guess if there were such this as "true perches" these guys would be it. This family includes darters, yellow perch, ruffe, walleye, zander etc. But anyway, I'll get to my point. The term "perch" is a term used loosly, like the term "shark" with freshwater catfishes and cyprinids. Not all perches are perches. The white perch is a member of the temperate bass family. The climbing perch is a gourami, the Sacramento perch is a sunfish.