Lake Victoria used to be very rich in fish, including many endemic species, but a large number of them have become extinct in the last fifty years.

 The main group in the lake is the cichlids (Haplochromis) with more than 500 species, almost all of which are endemic, including about 300 species still undescribed. This is far more fish species than in any other lake in the world (Lake Malawi is an exception).

The cichlids of Lake Victoria belong to an older group of more than 700 closely related species, which also includes the species of several smaller lakes in the region, notably Kioga, Edwards, George, Albert and Kivu.