Stocking density is considered a priority topic in aquaculture
research due to its bearing on the welfare of farmed fish and the need for
future recommendations governing stocking density management on fish
farms. This study was carried out to investigate the growth performance
and feed utilization response of sea bass (Dicentrarchus labrax) to
different stocking densities. Two duplicate groups of sea bass (mean
BW=32.83 g) were reared in six cages (2 m3 each) suspended at natural
pond with a proximate area of 20 hectare at three stocking densities (30,
45 and 60 fish/m3 equal to 1.0, 1.5 and 2.0 kg/m3) for 225 days.
Significant differences (P≤0.05) on final fish weight, weight gain
and daily gain were observed. Fish reared at the highest densities (60/m3)
had the lowest mean final body weight (225 g) while those of the lowest
densities (30/m3) showed the highest mean final body weight (270 g)
while (45/m3) are in between. The differences between the lowest and
higher density was 20%. A similar tendency was observed for SGR, 0.85
and 0.92 in the highest and lowest densities, respectively.
Significant difference in FCR were observed groups ranging from
2.76 to 3.24 by about 17% between the lowest and highest density.
Survival rate was insignificantly (P≤0.05) affected and was around 96%
independently of the density and the period. Part of the mortality
observed was due to fish jumping out of cages and other part after
sampling. Regarding economic efficiency the net returns of cage
improved with increasing density and the best net returns was observed
with the density 45/m3 followed by densities 60 and 30 fish/m3
respectively.
In conclusion the best density was 45 fish/m3 which improved by
33% than the lowest density (30 fish/m3, one kg/m3) and 17% than the
highest density (60 fish/m3, 2.0 kg/m3) for economical evaluation.