Jornal de Pesquisa e Desenvolvimento em Aquicultura

Abstrato

Effects of Stocking Density on Growth, Body Composition, Yield and Economic Returns of Monosex Tilapia (Oreochromis niloticus L.) under Cage Culture System in Kaptai Lake of Bangladesh

Mohammad Moniruzzaman *,Kazi Belal Uddin ,Sanjib Basak ,Yahia Mahmud ,Muhammad Zaher ,Sungchul C Bai

A 120-day research was conducted to evaluate the effects of different stocking densities on growth, body composition, survival, yield and economic returns of monosex male Nile tilapia, Oreochromis niloticus in net cages in Kaptai Lake of Bangladesh. Juvenile monosex tilapia with an average weight of 15.20 ± 0.15 g (mean ± SD) were randomly stocked in 12 floating net cages (3 m × 3 m × 2 m) at densities of 50 fish/m3 (T50), 75 fish/m3 (T75), 100 fish/m3 (T100) and 125 fish/m3 (T125) in triplicate groups. Fish were fed with a commercial pelleted floating feed (29% protein) at 3-5% of body weight, twice daily in all the treatments. The physico-chemical parameters of lake water were within suitable ranges for fish cultured in cages. After 120 days of trial, growth in terms of body final length, final weight, weight gain, percent weight gain, daily weight gain and specific growth rate of fish from T50 were significantly higher than those of fish from T75, T100 and T125. Feed conversion ratio was significantly lower in T50 followed by T75, T100 and T125 consecutively. Survival rate was not significantly different in T50, T75 and T100 while lowest survival was found in T125. Significantly lower amount of body lipid and carbohydrate contents were found in T125 than those of fish from T50, T75 and T100. Gross and net production levels from T100 were significantly higher than those from T50, T75 and T125. However, the benefit cost ratio from T50 was better than those from T75, T100 and T125. The results demonstrated that on the basis of growth and economic return 50 fish/cubic metre was the best stocking density for monosex tilapia culture in cages which might be technically feasible and economically viable.