Abstract:
The establishment of the introduced species in lakes Victoria, and Kyoga was accompanied by a
decline of most, and perhaps total disappearance of some, of the native fish species (OgutuOhwayo,
1994). Though the initial decline was due to overfishing (Jackson, 1971 ), predation
by Nile perch and competition with introduced tilapias contributed to the depletion of the native
fish stocks. Haplochromines were originally the most abundant fishes in both lakes and formed
at least 80% by weight of the demersal stocks of Lake Victoria (Kudhongania and
Cordone, 1974; Okaronon et al,1985). Lake Victoria had more than 300 haplochromine species,
more than 99% of them endemic (van Oijen et aI, 1984; Witte et aI1992). Each species had its
own unique combination of food and habitat preference (van Oijen, 1982; Goldschmidt et al 1990).