Effects of different stocking densities on the growth performance of Nile tilapia (Oreochromis niloticus L) fingerlings cultured in earthen pond system

Abstract

Fish culture is important to fill the demand of protein source foods and for contributing in poverty reduction in the country. The current experiment was conducted to explore the effect of stocking density on the growth performance and yield of Nile tilapia. Treatments had stocking densities of (2 fish) (control), (4 fish) and (6 fish) m-2. All treatments were in triplicates. Fingerlings with mean 7.96±0.2 g and 8.4±0.6 cm length were randomly stocked into 60 m2 earthen
ponds. The fish were fed on similar locally available feeds such as rice bran, Niger seed cake, soyabean cake and wheat bran for 300 days. The mean final weights of fish were (178.5±6.7 g), (191.5±5.7 g) and (168.7±4.6 g) for2, 4 and 6 fish m-2 respectively. The length-weight relationship between the treatments showed strong correlation (R2>0.9) and the growth parameter ‘b’value were indicated negative allometric growth pattern (b<3) in all treatments and showed nonsignificant differences (χ2, p>0.05). The survival rate (%) was ranged (73-87.2) showed a significant difference when increasing in stocking density (p<0.05). The feed conversion ratio was ranged (1.84-3.4) showed significant difference (p<0.05). However, SGR (% day-1 and g day-1 ranged 1.0-1.1 and 0.59-0.64 were not density dependent for all treatments (p>0.05). The gross yield (55-123.8 kg pond-1) revealed significant differences as the stocking density increases (p<0.05). In conclusion, it is possible to grow 4 fish m-2 in addition to 2 fish m-2 (control) for larger size fish demand while 6 fish m-2 gives higher gross production with supplemented feed.