Food habits of tilapiine cichlids of the Upper Zambezi River and floodplain during the descending phase of the hydrologic cycle

Habitat use and diets of five tilapiine populations of the Upper Zambezi River Basin in Zambia, south-central Africa, were examined during the 8 month descending phase of the annual hydrological cycle. All species occurred across a range of habitats, with most individuals captured from lagoons. Tilapia rendalli, a macrophyte feeder, was the only dietary specialist. Ontogenetic diet shifts were not observed over the size range examined (30–320mm LS). Algae were uncommon in tilapiine diets. Tilapia ruweti, the smallest tilapiine in the region, was the only species that consumed more algae (filamentous algae) than detritus. Oreochromis andersonii, Oreochromis macrochir and Tilapia sparrmanii had high dietary overlap and occurred in the same habitats in similar relative abundances. High overlap in habitat use and diet among tilapiines contrasted with findings from a comparable analysis of predatory haplochromine cichlids of the region that revealed strong ecological segregation and niche complementarity during the annual descending-water phase. # 2003 The Fisheries Society of the British Isles