What is the scientific name of a perch?

It depends which perch you are talking about. There are many fishes which are commonly called perch. In the United States, perhaps one of the more common true perches is the yellow perch, Perca flavescens, (Family Percidae, Order Perciformes). But there are numerous other perch-like fish within this order, including white perch (Morone americana, actually a type of bass, Family Moronidae), silver perch, (Bairdiella chrysoura, a drum in Family Sciaenidae), and the very large, invasive predatory fish the nile perch, from the Nile River (Lates niloticus, Family Latidae), which grows to over 400 pounds!