1. The algal-grazing species Haplochromis obliquidens Hilgendorf 1888, H. nigricans (Boulenger) 1906, and H. nuchisquamulatus (Hilgendorf) 1888, are redescribed on the basis of new and more extensive collections.
2. A new species, H. lividus, apparently related to H. obliquidens is described.
3. Data on the food and ecology of these species are given.
4. Consideration is given to the possibility of recognizing a number of supraspecific groups of Haplochromis in Lake Victoria. At present, although such groups may be determined, it is impossible to give them formal taxonomic status.