 By far the largest Lake Victoria group are the haplochromine cichlids, with more than 500 species, but at least 200 of these (approximately 40%) have become extinct, and many others are seriously threatened.Initially it was feared that the percentage of extinct species was even higher, but some species have been rediscovered after the Nile perch started to decline in the 1990s.Some species have survived in nearby small satellite lakes, or in refugia among rocks or papyrus sedges (protecting them from the Nile perch), or have adapted to the human-induced changes in the lake itself.