Abstract
Horizontal eyes and head movements made by three carnivorous fishes swimming in an experimental channel were recorded cinematographically and analyzed frame-by-frame. Though the eyes sometimes moved with the head, the approximate stable orientations of eyes, making slight fluctuations within one or two degrees, were observed in the traces of eye movements. Depending on the assumption that a few flicks made between the stable ocular orientations do not interfere with recognition of the visual images, the compensation was considered to be perfect. It was concluded that, while swimming even at relatively high speed, the rainbow trout, largemouth bass, and bluegill are capable of keeping image stable for 1.06 seconds, 0.90 seconds, and 0.28 seconds respectively.