Résumé
Morphometric and allozyme variation of nine natural populations and three cultured strains of Oreochromis niloticus has been studied. Natural populations from West Africa and the Nile, identified as the same subspecies, O. niloticus niloticus, differed significantly. The Nile populations are genetically closer to the population from Lake Edward, identified as O. niloticus eduardianus. Morphological differences were observed between natural populations and their cultured strains. These are undoubtedly related to ecophenotypic influences, because cultured strains are genetically related to their natural parental populations.