Four indices for comparing the overall growth performance of fishes ( omega , P, Phi , and Phi ') proposed by various authors are assessed, based on growth parameter estimates in 100 populations of tilapia in 15 species of the genera Tilapia, Sarotherodon and Oreochromis , from inland waters in Africa and Asia. The best index, i,e., the one whose distribution was most similar to a normal distribution was Phi ' (= log 10K + 2 log 10L sub( infinity )); the worst index was omega (K=L sub( infinity )). The best growth performance in all populations investigated was in Oreochromis niloticus) from Lake Kainji, Nigeria, the worst in .O. mossambicus from Lake Sibaya (South Africa). Some theoretical and practical implications of these findings are discussed.