Female pirate perch (Aphredoderus sayanus) were more numerous and grew faster in their second and third years than males. The life spans of the sexes were about equal and did not exceed 4 years. Total length (L, mm)-weight (W, g) relationships of the sexes did not differ, and the combined equation for 419 fish is W = 0.0000376L2.768. Frequent food items were Cladocera (particularly for young of the year), aquatic Diptera larvae, Isopoda, and Amphipoda.