Development of sustainable cage cultre practice for tilapia (oreochromis niloticus l.) in riverine ecosystem

Abstract

This study was conducted in the Dakatia river at Echoli and Roghunathpur site of Chandpur, Bangladesh during the year from 2010 to 2011 which consisted of four trials under the two experiments on stocking density and feeding regime of tilapia (Oreochromis niloticus) in cage culture. Each experiment include two trials with complete randomized design (CRD). Floating net cages, having an area of 3m×3m×2m in each were installed in both sites of the Dakatia river. The initial average weight (g) of 32.31±9.59, 28.92±8.37, 36.20±11.64 and 20.76±6.14 were stocked for each treatment of the stocking density trial-1, stocking density trial-2, feeding regime trial-1 and feeding regime trial-2 respectively. The duration of each trial was 120 days having three treatments with three replications to assess sustainable cage culture practice for tilapia in the riverine ecosystem. The physicochemical parameters of cage water were monitored fortnightly. Final weight (g), weight gain (g), relative growth rate (%), specific growth rate (%/day), food conversion ratio and survival rate (%), gross production (kg/cage), net production (kg/cage), net profit (Tk/cage), benefit cost ratio of tilapia in cages were determined after completion of the each trial. Growth parameters such as weight gain (g), relative growth rate (%), specific growth rate (%/day), and food conversion ratio was also measured monthly basis. The physicochemical parameters of cage water were found suitable for cage fish culture in all the trials. Correlations of different physicochemical parameters were related to each other and the relationship was found significant in most of the parameters. All growth parameters of stocking density trial-1 revealed highly significant differences (p < 0.001) among three treatments. The maximum survival rate was found in T (85.61%) followed by T 2 (81.92%) and T (67.58%) respectively, having highly significant differences (p < 0.001). The highest benefit cost ratio was achieved in T 3 (1.20) followed by T 2 (1.19) and T 3 (0.88) but highest profit was found in the T 2 1 . In stocking density trial-2, it was exhibited that all growth parameters were highly significant differences (p < 0.001) among three treatments. The highest survival rate was found in T 1 (97.92%) followed by T (86.73%) and T (84.38%) respectively which was highly significant differences (p < 0.001) among them. The highest benefit cost ratio was achieved in T 3 1 (1.81) followed by T (1.37) and T 3 (1.07) respectively. The net profit was found similar as highest in T and followed by T 2 and T . In case of feeding regime trial-1 the final weight, weight gain and specific growth rate showed significantly different (p < 0.05) among the treatments, while the relative growth rate and food conversion ratio was found highly significant differences (p < 0.001) among three treatments. The highest survival rate was found in T 3 1 1 2 (97.33%) followed by T (96.88%) and T (96.44%) respectively which was not significantly different. The maximum benefit cost ratio was achieved in T 2 1 (1.71) followed by T 2 (1.36) and T (1.17) respectively, which was similar as achieved net profit of the three treatments. The final weight, weight gain and specific growth rate of feeding regime trial-2 were exhibited significant differences (p < 0.01) among the three treatments, whereas the relative growth rate and food conversion ratio was found highly significant differences (p < 0.001) among three treatments. The highest survival rate was found in T 2 (97.22%) followed by T 1 3 (97.00%) and T (96.66%) respectively but not significantly differ with each other. The highest benefit cost ratio was determined in T 3 (1.93) followed by T 2 (1.44) and T (1.25) respectively, which was similar as determined net profit. The proximate composition of used floating feeds was found suitable for tilapia culture but the crude protein (%) showed some differ from labeled crude protein. It could be concluded that stocking density of 50/m 1 3 and feeding regime with 4% of body weight feed through the culture period was found suitable for practice tilapia cage culture in the riverine ecosystem.