Diet of adult pikeperch Sander lucioperca, Eurasian perch Perca fluviatilis, northern pike Esox lucius and European catfish Silurus glanis as top predators in aquatic ecosystems in Serbia was investigated during 2011, in order to understand their relationship to their prey and to investigate their food consumption, feeding and assimilation rate, cannibalism, and habitat segregation. Northern pike, Eurasian perch, pikeperch and European catfish were collected in three reservoirs in Serbia. Prey items that were found in all four species included fish, mollusks, insect larvae and crustaceans. A total of 11 taxonomic groups were found, but they were not all represented as a prey in all four species. Eurasian perch were present in the diet of all four predatory fish species, mollusks were recorder only in that of European catfish. Roach Rutilus rutilus and bleak Alburnus alburnus were prey to all species, except northern pike. Chub Squalius cephalus, bream Brama brama and Gammaridae were found only in stomach of pikeperch. Analysis of similarity showed that difference for diet between predatory fish species was significant for their due to significant differences existing between northern pike and pikeperch and northern pike and Eurasian perch.