Effect of stocking density on growth performance and gonadal maturity of all-female giant freshwater prawn, Macrobrachium rosenbergii

All-female stocks of giant freshwater prawn, Macrobrachium rosenbergii, hold immense potential for aquaculture but early sexual maturity might still be a constraint in all-female prawn farming. The growth performance and gonadal maturation of all-female M. rosenbergii reared in 1,000 L tanks for 60-days were tested at five stocking densities of 4 (T1), 8 (T2), 16 (T3), 24 (T4), and 32 (T5) prawns/m(2) in triplicates. The mean initial weights (+/- SD) of prawns were 5.20 +/- 0.42 g (T1), 5.10 +/- 0.48 g (T2), 5.18 +/- 0.54 g (T3), 4.87 +/- 0.92 g (T4), and 5.05 +/- 1.09 g (T5), respectively. The survival rate (83.3%), mean final weight (24.93 g), daily weight gain (0.33 g), and specific growth rate (2.61) were the highest in T1, while the most efficient feed conversion ratio (1.57) was in T2. The prawn yields were higher at higher stocking densities (T3 to T5). The stocking density of 8 prawns/m(2) is feasible for good growth performance, while the estimated density for optimum yield was 23.5 prawns/m(2), indicating that all-female prawns are amenable to intensive farming. The presence of virgin females ranged from 30% in T1 to 14% in T5, but the distribution of ovarian stages was not significantly different among the stocking densities tested. The gonadosomatic index values showed no significant difference among the treatments. The results indicated that while the stocking density significantly affected growth parameters, it had no significant effect on the all-female prawns' gonadal maturation.