Zooplankton was the only food component of common bream and silver bream, and the main food component of roach and bleak in the pelagic zone of the Dobczyce Reservoir (southern Poland) from April to October 1994. Cladocera and Copepoda constituted 67.9% of the food consumed by the whole fish community. The average size of eaten individuals ranged from 0.62 to 1.43 mm. Planktivorous fishes selected phytoplankton-controlling filtrators, mainly large Daphnia species, which were eliminated most effectively in the summer.