Foraging of rocky habitat cichlid fishes in Lake Malawi: coexistence through niche partitioning?

The haplochromine cichlid fish communities of the rocky habitats of Lake Ma lawi are highly diverse; however, many species live side by side with appar ently very similar resource requirements. There is a longstanding debate co ncerning whether these species partition their resources on a finer scale t han has been previously reported or if species that are truly ecologically indistinguishable can coexist. A field study of food resource use was condu cted to determine whether coexisting species segregate their diet and forag ing sites. Significant differences between species were found, yet consider able inter-specific resource use overlap was commonplace. The data indicate that these cichlid species coexist both with and without niche differentia tion. We propose that alternatives to niche differentiation should be consi dered to explain how many species coexist in Lake Malawi cichlid communitie s.