The faunal dietary composition of Ilisha Africana (Bloch, 1795) in Qua Iboe estuary, Nigeria, comprised primarily mysids and decapods crustaceans while fish eggs were of secondary importance. Other dietaries (amphipod, clupeids, unidentified fish, fish larvae, cephalopods, polychaetes, nematodes) were of incidental importance. Overall food richness and diversity (Bn) were low, depicting that I. africana is an oligophagous carnivore; this feeding regime was maintained throughout the dry (November-February) and wet (March-October) seasons in spite of slight short-term (month-to-month) variations. There was a positive relationship between reproductive investment and Bn whereas fat index (FI) decreased with increase in Bn. Diet diversity was higher in the dry season than during the rains; this conformed to the optimal foraging theory when viewed vis-à-vis the cycle in food resources availability and abundances in tropical aquatic systems. Foraging performance (FP) was higher in the wet season than during the dry season. It was inversely related to Bn but positively to FI. Seasonality in FP was linked with the breeding cycle of the fish.