Some aspects of the reproductive strategy of Ilisha africana (Bloch, 1795) in Qua Iboe estuary, Nigeria, were studied between November 1987 and October 1988 inclusive. I. africana is a monomorphic species. Sex ratio was strongly female-biased with no marked seasonal switches but there were significant ontogenetic and monthly heterogeneities. Females attained sexual maturity at a median size of 15.4 cm TL (range 6.5-21.0 cm TL). Gonadosomatic index decreased with increasing fish size and fat index. Investment in egg weight increased with ovary weight and gonadosomatic index but decreased with increasing total/standard lengths and total/somatic weights. Breeding was year-round, with maximum and minimum intensities in December and March, respectively. Mean fecundity was 6,716 eggs (rage 2,141-12,602 eggs); it increased with fish total/standard lengths and total/somatic weights but decreased with increasing egg weight, gonadosomatic and condition indices. These attributes depicted trade-offs between growth and reproductive investment and between the latter and lipid energy reserves. There were also trade-offs between fecundity and reproductive investment, egg quality and the relative well-being of the fish. The reproductive life history of I. africana, which incorporates the r- and k-selection traits, is considered as a strategy adopted to equilibrate the optimization of reproductive success and enhanced potential of progeny survival.