Lake Naivasha is a shallow, freshwater lake in the eastern Rift Valley of Kenya. Its fish community now comprises only introduced species. Oreochromis spirulus niger was stocked in 1925 as a forage fish for the largemouth bass, Micropterus salmoides , introduced in 1929 for sport fishing. Further introductions of tilapiines followed for commercial exploitation. A gillnet fishery opened in 1959, and the annual species catch com...