Food habits and foraging behaviour of benthivorous cichlid fishes in Lake Tanganyika

Abstract

A study was made of the food habits and foraging behaviour of coexisting benthivorous cichlid fishes along the rocky northwestern coast of Lake Tanganyika. The five group-foraging species regularly found in the study area,Gnathochromis pfefferi, Lamprologus callipterus, Altolamprologus compressiceps, Lepidiolamprologus elongatus andLobochilotes labiatus, have different foraging techniques, although all eat shrimps (family Atyidae). Individuals of each species allow potential food-competitors to forage within its foraging area, increasing its own chances of finding shrimps disturbed by the foraging action of such competitors. In these five shrimp-eating species, group foraging thus occurs in a mutualistic context. A super-abundance of shrimps may allow the coexistence of shrimp-eaters with different foraging techniques, and furthermore, their coexistence itself may promote cooperative group-foraging among them. Three benthivorous cichlids,Neolamprologus mondabu, N. tretocephalus andN. leleupi, were indifferent to, or excluded, the group foraging species because these three individual-foraging species exploit different food items or employ similar foraging techniques to the group-foraging species.