The fieldwork for the present paper was carried out during three months, from July to September 2011, with a view to carrying out a study on the variation in diet according to the sizes of Labeobarbus altianalis, Cyprinidae of Lake Edward. Fish were collected using 7.5cm mesh gillnets, 5cm mesh beach seines, fiknet fishing, line fishing with hooks using appropriate bait and baskets. The analysis of stomach contents allowed us to conclude that the diet of Labeobarbus altianalis of small size (10 to 31 cm) is essentially composed of insects while that of Labeobarbus altianalis of larger size (32 to 77 cm) is made up of fish. Plant debris is consumed by both small and large Labeobarbus altianalis.