Impact of Sargochromis codringtonii (Teleostei: Cichlidae) on pulmonate snails in irrigation ponds in Zimbabwe

Abstract

The impact of Sargochromis codringtonii on pulmonate snails, including those that transmit schistosomiasis, was assessed over 29 months in 2 800m² irrigation ponds. Snail populations in fishless ponds were first monitored for 10 months before 85 S. codringtonii were introduced into each of three ponds and the molluscicide niclosamide was applied at a dose of 1ppm to another three ponds. Although Sargochromis codringtonii populations increased to 85–400 per pond, they did not have a significant effect on snail populations, whereas niclosamide had a significant and sustained negative effect on them. S. codringtonii was the only snail-eating fish in the study ponds. The failure of the fish to impact negatively on snail populations was attributed to low fish population density and a relatively short observation period. Further work on S. codringtonii as a biological agent for snail control in shallow irrigation ponds is recommended.

African Journal of Aquatic Science 2007, 32(2): 197–200