Northern pike confined in tanks and aquaria were presented various species and sizes of food fishes. The optimum size of centrarchids eaten by 7‐ to 12‐inch northern pike was 1.5 inches, and by 13‐ to 23‐inch northern pike 2.5 inches. The northern pike selected minnows and chubsuckers over centrarchids and yellow perch. They showed no choice between centrarchids and yellow perch, but selected centrarchids over bullheads. These results increase doubt as to the effectiveness of northern pike for controlling pan fish populations in lakes, and suggest that large populations of appropriate size soft‐rayed food fishes favor good growth of northern pike.