Temperature requirements are reviewed for three North American percids (walleye, Stizostedion vitreum; sauger, S. canadense; and yellow perch, Perca flavescens), three Eurasian percids (perch, P. fluviatilis; pikeperch, S. lucioperca; and ruffe, Gymnocephalus cernua), and nine cohabitant fish species for comparison. Whole-organism responses are described for each species--primarily concerning reproduction, growth, survival, and activity. The percids are classified as temperature mesotherms and hey are arranged in order of their thermal requirements as follows: pikeperch perches and ruffe sauger walleye. Perca and Stizostedion spp. are annual spawners with synchronous oocyte growth during fall through winter, culminating in spring spawning. Maturation occurs below 12(C). Spawning occurs from late February to early July at 2-26(C) over their geographic ranges. Oocyte growth of ruffe is asynchronous, accelerated by warm temperatures; batch spawning occurs over a prolonged period, from mid-April through July at 11-18(C). Physiological optima range from 22(C) for sauger and walleye to 25(C) for perch and 27(C) for pikeperch. The ultimate upper incipient lethal temperatures of percids range from 29 to 35(C), depending on species and experimental conditions.