Morphometric and allozyme variation in natural populations and cultured strains of the Nile tilapia Oreochromis niloticus niloticus (Teleostei, Cichlidae)

The morphometrical and allozyme variation of nine natural populations of Oreochromis niloticus and three of their cultured strains has been studied. Differences in external morphology and in allozymes were noted between natural populations from West Africa and from the Nile. Although both are arranged in the same subspecies, O. niloticus niloticus, the Nile populations are closer to the population from Lake Edward, identified as O. niloticus eduardianus. Morphological differences have been observed between natural populations and their cultured strains. These undoubtedly are related to ecophenotypical influences, because cultured strains are genetically related to their natural parental populations.