Growth of heat-shock induced triploids of blue tilapia, Oreochromis aureus, reared in tanks and in ponds in Eastern Congo: feeding regimes and compensatory growth response of triploid females

In this study, triploids of Oreochromis aureus were obtained via the heat-s hocking method. Triploid fishes were effectively sterile and predominantly female (80%). Diploid and triploid fishes were reared in tanks or ponds rec eiving organic manure. In tanks, the survival rate was 65.3% and 60.7% for diploids and triploids, respectively. Triploids, mostly females, grew slowe r (P < 0.05) than diploids consisting of almost equal number of females and males. In ponds, a significant difference in body weight (P < 0.05) in fav our of diploids was also recorded, but both lines grew slower than in tanks . In another tank trial, growth of diploid and triploid females was compared using a normal feeding regime (7 days/week of feeding) or a restricted feed ing regime (5 days/week of feeding). A little difference in growth was reco rded in favour of triploids under the normal feeding regime. However, a hig h significant difference (P < 0.001) between diploids (71.8 +/- 5.8 g) and triploids (118.5 +/- 8.9 g) was recorded under the restricted feeding regim e. While the diploids under the restricted feeding regime grew slower than diploids under the normal feeding regime, no difference in growth between t riploids in the normal and restricted feeding regime was observed. (C) 2001 Elsevier Science B.V. All rights reserved.