Simulated Field Trials to Evaluate the Effect of Sargochromis codringtoni and Tilapia rendalli on Snails in the Presence and Absence of Aquatic Plants

Abstract

Two cichlid fish were studied under semi-natural conditions to evaluate their potential as agents for the biological control of schistosome intermediate host snails. Sargochromis codringtoni is known to eat snails, whereas Tilapia rendalli survives primarily on aquatic plants but may ingest snail egg masses and juvenile snails. Sargochromis codringtoni reduced snail numbers significantly, but this effect was less pronounced when plants were present. Tilapia rendalli did not significantly reduce the biomass of aquatic plant species used in the experiment, but did significantly reduce snail numbers, albeit to a much lesser extent than observed for S. codringtoni. It was concluded that the two fish species may complement each other in the control of schistosome intermediate host snails, but further investigations are needed to determine: whether they can co-exist in nature, and the extent to which T. rendalli can control other species of aquatic plants under natural conditions.