Abstract
Increase in stocking density of fish is one way to optimize productivity in intensive rearing system. However, high rearing density is a
potential source of stress that may constrain fish growth. In order to investigate this detrimental effect on growth and survival, the
juveniles of Therapon jarbua were studied under various stocking densities. Five groups of juveniles of T. jarbua (mean initial weight
3.10.07 g and total length 13.10.1 mm) were reared in seawater tanks of 0.06 m3
at different densities (10, 20, 30, 40 and 50 fish)
for 45 days. The juveniles were fed three times a day with a compound diet of 40% protein. Differences in food consumption, mean
body weight gain and survival rate of the stocking groups were found throughout the experimental period. At highest density (50-
fish/0.06 m3
) fishes showed the lowest growth and survival rates with low feed conversion efficiency. Maximum growth rate (4.49
g/fish/day) was obtained at the optimum stocking density of 39 juveniles per 0.06 m3
. Statistical analysis showed that the growth rate
was a quadratic function of stocking density: Ĝ = 1.1733212 + 0.0025563 D – 0.0005260 D2
, while the estimated survival rate showed
a linear model of Ŝ = 0.5108531 – 0.0042239 D, indicating that the survival rate was negatively proportional to the stocking density.
Feeding cost for optimum stocking density (39 fish/0.06 m3
) at feeding rate of 2% wet body weight gives a cost of Rs. 48.00 per kg
biomass.
