Nine major trophic groups (Hydrocynus vittatus, Synodontis zombezensis, cichlids, Limnothrissa miodon, mussels, zooplankton, phytoplankton, macrophytes and periphyton) were analyzed using the ECOPATH II model to assess the trophic interrelationships and community structure of Lake Kariba, Zimbabwe. The utilization of energy flows, represented by the ecotrophic efficiencies vary widely among the various groups. The production of S. zambezensis, of macrophytes and of the periphyton is apparently little utilized within the system and thus S. zambezensis represents a potentially important resource. The utilization of H. vittatus and of the cichlids is moderate, but this inference depends on the reliability of the catch data. The small pelagic Limnothrissa miodon is fairly heavily harvested, although the analysis indicates that fishing mortality could be increased. This, however, depends on the reliability of the P/B ratio. The pelagic food chain appears fully utilized whereas there is no room for herbivorous species in the vegetated littoral zone. These two habitats are new to the original riverine fish fauna and only the former has become productive after the introduction of the pelagic L. miodon.