Common forage fishes were fed to black basses, Micropterus dolomieui and Micropterus salmoides, to obtain food conversion factors. The exptl. bass were held in glass aquaria, supplied with running natural water of Golden Lake in the Upper Peninsula of Michigan. The avg. food conversion factor of seven bass measuring from 3.7 inches to 10.2 inches was found to be 3.9 (pounds of forage fish required per pound weight gain of bass).