Genetically improved farmed tilapia (GIFT) has undergone ten generations of selection for harvest body weight in Malaysia, but there have been no reports on genetic parameters for flesh characteristics for this strain. In this study the effects of selection for increased harvest body weight on flesh chemical composition (protein%, fat%, moisture% and pH) as well as in colour, were investigated in fillets from fish of the GIFT strain. Heritabilities and genetic correlations of flesh characteristics with body dimensions (weight, length, width and depth) and with fillet traits (weight and yield) were also estimated. Body dimensions were of interest because if they were related to fillet weight and fillet yield (FY), they could be used as predictors of the latter traits in live fish instead of slaughtering the animals.