Survival rates of tilapia, Oreochromis spilurus (Günther), fingerlings reared at high densities during winter using warm underground sea water

The study was conducted to determine the optimum stocking density for rearing tilapia. Oreochromis spilurus (Günther), fingerlings in tanks during winter using warm (21-26°C) underground sea water (37%o). Seawater-acclimated fingerlings with mean weight of 2 g were stocked in eighteen 400-1 fibreglass tanks at 750 and 1000 fish m−3. Fish were fed at the rates of 2.5, 3.0 and 3.5% day−1 of the fish biomass. After 83 days, the mean individual daily weight gain was significantly higher (P < 0.028) at stocking of 750 fish m−3 than at 1000 fish m−3. Feed conversion ratio was significantly higher at stocking of 1000 fish m−3 than at 750 fish m−3 and at feeding rate of 3.5% day1 than at 2.5% day−1. However, because no significant differences were observed on survival rates between the two stocking densities and among feeding rates, it is recommended that the stocking density of 1000 fish m−3 and a feeding rate of 2.5% day−1 be used for optimum production of tilapia fingerlings in tanks during winter using warm underground sea water.