Potential of Metriaclima lanisticola (Teleostei: Cichlidae) for biological control of schistosome intermediate host snails

Metriaclima lanisticola, a native cichlid of Lake Malawi, was studied under laboratory conditions to evaluate its possible role as a predator of snails (Bulinus spp.). Bulinus globosus, B. nyassanus and B. tropicus were used as prey. B. globosus and B. nyassanus are intermediate hosts of human schistosomes in Lake Malawi. M. lanisticola orally shelled snails of all three species. Even when small snail sizes were offered, the fish shelled them. This suggests that M. lanisticola is entirely an oral sheller. Opercula of Melanoides species were commonly found in the stomach contents of wild-caught M. lanisticola, while whole snail shells or shell fragments were never observed, further suggesting that the fish is an oral sheller. M. lanisticola consumed more B. nyassnnus in aquaria without substratum than in aquaria with a sandy substratum and apparently the fish is dependent on visual perception for prey detection.