Cuckoo among Lake Malawi cichlid fish

Abstract

THE family Cichlidae consists of bony, perch-like fish which are found in many of the fresh waters of America, Africa and Asia. In Africa most of the almost 700 species occur in the Great Lakes. Approximately 300 species are known in Lake Malawi and 98% of them are endemic to it. Like cichlids from elsewhere, they have intricate but stereotyped territorial and courtship behaviour, followed by spawning and a period of parental care¹. Substrate spawners lay their eggs on the substratum or a suitable object and both parents guard the eggs and later the developing fry^1,2. In Lake Malawi the only known substrate spawner is Tilapia rendalli Dumeril, a non-endemic species. Evidence suggests that all other cichlids of Lake Malawi are maternal mouthbrooders. When eggs are laid they are picked up by the females and brooded in the mouth^1,2. When fry are ready to emerge the parent releases them at a suitable site and usually remains to guard her brood, recalling them into her mouth in the event of danger^1,2. After several days, fry no longer respond to their mother's recall signals and the association is terminated. Although cichlid parents usually guard their fry ferociously it seems that at least one species passes these parental duties on to other species of cichlid.