(Comparative studies on the growth of Oreochromis, (Osteichthyes, Cichlidae) in monosex culture. II í Length and weigth growths and Biomass yield)

Abstract

The purpose of this study is to verify the economical viability of the monosex cultivations, through the comparative analysis of the length and weight growths, and biomass yield in cultivation of male hybrids (ââ„¢"š O. hornorum x ♀O. niloticus) and of males and females of O. niloticus. Fries were stocked in ponds of 100 m² where the stocking rate was two individuals/m². Biometric data were obtained through monthly samples of 25% of the population of each pond. It was observed that the gain in length and weight were similar both in hybrid males and O. niloticus males, and superior of the females. The mean length and weight "increment" was, respectively, 0.074 cm/day and 2.14 g/day for males cultivations, and 0.050 cm/day and 1.05 g/day for females. Economical analyses of the cultures considering only the ration expenses, showed for the male cultivations a profit about twice that reached by the females. The final production was approximately 140 kg/100 m² year for males, both hybrid and O. niloticus, and 70 kg/100 m² year for females.