Common and different morphological aspects , discriminant methods of Nile tilapia (Oreochromis niloticus), blue tilapia(O .aureus)and their hybrid (O .niloticus ♀×O .aureus ♂) were reported .Morphological differences of hybrid and their parents were comprehensively analyzed by χ2 -test of 8 meristic characters , and by clustering analysis , discriminant analysis and PCA of 9metric plus 24 truss network characters .The hybrid resembled blue tilapia from body color , but it resembled Nile tilapia from the results of three multivariate analysis in body shape by different combination of genes.Genetics of body color and body size were controlled by different combination of genes . Discriminant functions were formed to identify Nile tilapia , blue tilapia and their hybrid .