A study to determine the relation of zooplankton abundance to growth of young yellow perch was conducted in Oneida Lake, New York, during late summer of 1968 to 1971. Daphnia species were the principal components of the zooplankton and fish stomachs. Annual variations in consumption and growth by young perch were closely correlated with abundance of Daphnia. The total daily consumption of Daphnia pulex by the young perch approached 17% of the standing crop when young perch were most abundant. The vertical distribution of D. pulex may increase its vulnerability to predation by young perch. Although predation by the perch population may modify Daphnia populations, qualitative and quantitative variations in the zooplankton occur independently of perch predation and control the growth rates of young perch.