Stocking density effect on Nile tilapia (<em>Oreochromis niloticus</em> L.) fry performance during sex reversal

Abstract

To study the effects of stocking density on the performance of newborn fries of Nile tilapia Oreochromis niloticus, during sex reversal stage in green waters, 1500 fries were stocked with 12.41mg of average weight and 9.38mm of total average length in hapas of 12,5 litres, at densities of 2, 4, 6, 8 and 10 fries/litre, in a completely randomized design with 4 replications. They were fed with a fine commercial diet containing 43% CP, and 60mg of methyltestosterone/kg, six times a day, during 28 days. The density increase resulted in lower final average weight and length defined by regression models. The effect of density on the growth decrease started to be significative on the second week of rearing, while the total biomass and feed conversion were increased with the density increase. Survival, condition factor and coefficient of variation were found to be density independent. It is concluded that 2 fries/litre must be used to produce bigger fingerlings, but larger densities can be used, obtaining smaller fingerlings, however incrementing total biomass.