Larvivorous potential of fish species found in river bed pools below the major dams in Sri Lanka.

Malaria in Sri Lanka is closely associated with the river systems in the country. Construction of major dams across rivers has resulted in year-round pooling and anopheline mosquito breeding in river beds below the dams. This study was carried out to determine the larvivorous activity of fish found in river bed pools below the dams to identify the potential fish species for anopheline larval control in these areas. Fish species in five river beds below the dams, namely, Laxapana, Kotmale, Nilambe, Victoria, and Rantembe, were identified in June 2000. The larvivorous potential of the 12 fish species collected was determined in the laboratory based on the number of larvae consumed per fish within 10 min and an hour. Danio malabaricus Jerdon, Oreochromis mossambicus Peters, Oreochromis niloticus L., and Poecilia reticulata Peters consumed nine or more larvae per fish within 10 min. Aplocheilus dayi Steindachner and Rasbora daniconius Hamilton consumed nine and eight larvae, respectively, within 1 h. O. mossambicus, O. niloticus, and P. reticulata consumed 10 larvae per fish within 10 min. Despite some species having a high larvivorous potential in the laboratory, field studies are required to determine the feasibility of using these fish for anopheline mosquito control in the river bed pools below the dams.