The final weight of fish differed significantly among the fish treatments (p = 0.021) ( Table 1). The improved F6 and F5 strains did not differ in their final mean body weight (F6: 23.41 g vs F5: 21.84 g, p = 0.100) but both had higher final mean weight than the unimproved strain (18.70 g). The proportion of this difference which could be attributed to selection was calculated and estimated to be 16.8% gain between the unimproved strain and the F5 and 25.2% between the unimproved strain and the F6.