Comparative analysis of growth performance, feed utilization, and antioxidant capacity of juvenile mud crab, Scylla paramamosain, reared at two different conditions

This study was carried out to analyse the growth performance, feed utilization, and antioxidant capacity of juvenile mud crab (Scylla paramamosain) reared in two conditions. Here, a new indoor polypropylene tank culture system and a traditional outdoor pond cage facility were used to perform feeding experiments on juvenile crabs. After eight weeks, the survival rate, weight gain, moulting rate and feed efficiency of crabs cultured in polypropylene tanks were markedly higher than those cultured in pond cages. Moreover, the activities of serum acid phosphatase (ACP) and alkaline phosphatase (ALP), and the antioxidant indices including glutathione peroxidase (GSH-PX), glutathione transferase (GST), superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) in hepatopancreas were higher in crabs cultured in the polypropylene tank system than those in pond cages. Based on these results, compared with the traditional pond cages, the polypropylene tank culture system is more suitable for the short-term culture of mud crabs.

Water quality, growth and production performance of stinging catfish, Heteropneustes fossilis (Bloch) in cemented tanks with two different stocking densities

Attempt has been taken to develop intensive tank culture technique providing natural environment for Stinging catfish (Heteropneustes fossilis) inside tank to increase survival rate as well as production. The experiment was conducted for a period of 150 days in two tanks (T1 and T2) of 300 m2. Fish fries with a mean weight and length ranged from 1.02 to 2.2 g and 2.7 to 3.5 cm were stocked in T1 and T2, respectively. Stocking density of fingerlings were 1, 25,000 and 1, 50,000 per Ha in T1 and T2, respectively. Commercial pelleted feed was supplied to tank reared fish twice daily at a rate of 3-10% of body weight per day and later feeding rate was adjusted based on body weight by sampling. Important water quality parameters (temperature, DO, pH, transparency, ammonia and nitrate) were recorded weekly throughout the culture period. Survival rate was 87% and 84% in T1 and T2, respectively. Mean final weight were 41.73 ± 2.09g and 40.6 ± 0.90 g in T1 and T2, respectively. Length-weight relationship indicates that the growth rate was always higher in T1 followed by T2. Results showed that net yield was relatively higher in T2 (5115.35 ± 113.13 Kg/ha) than T1 (4537.12 ± 227.4 Kg/ha). In case of production, there was significant difference (p < 0.05) between two treatments. This experiment demonstrated the potential of H. fossilis production through new technique of tank culture system. However, more research is needed using local feed ingredients with higher stocking density. Bangladesh J. Zool. 47(1): 107-119, 2019

Growth, survival and intactness of green mud crab (Scylla Paramamosain) broodstock under different captive grow out protocols

Development of broodstock of the green mud crab (Scylla paramamosain) was assessed under three different captive growout protocols viz. in the open fibre glass tanks (T1), in plastic boxes (T2) floating on fibre glass tanks and in plastic drawer/compartment (T3) for a period of 5 months under the Centre for Marine and Coastal Studies (CEMACS), Universitiy Sains Malaysia (USM). The male (M) and female (F) mud crab were cultured separately to maintain virginity. Suitability of both the sexes were evaluated considering the weight gain (size), survival and intactness of limbs during harvesting. Result of the present study revealed that, irrespectives of growout protocols, growth of mud crab happened following the sigmoid pattern. A noticeable intersexual weight attainment was observed with significantlyhigher (p<0.05) weight gain for the males. Meanwhile, growth was influenced by the culture protocols for both the sexes with significant (p<0.05) weight gain in outdoor tanks (M= 319.75 g, F= 246.17 g) followed by outdoor floating boxes (M= 250.50 g, F= 198.70 g) and indoor compartment (M= 246.40 g, F= 178.50 g). Survival and the proportion of intact crabs under indoor compartment and outdoor floating boxeswere significantly higher (p<0.05) than out door tank culture system. The result of the present study suggested that, outdoor growout protocol could be followed for faster broodstock development purposes to reduce the dependence on natural broodstock for hatchery operations.SAARC J. Agri., 16(1): 169-180 (2018)

Modified photoperiods and light intensities for grow-out production of nile tilapia (O. niloticus) under indoor tank culture system

The study aimed to evaluate the effect of modified photoperiods and light intensities on grow-out production of tilapia under indoor tank culture system; specifically on water quality and on growth performance of tilapia. The study was conducted inside the greenhouse and considered two factors: photoperiod (24L:0D, 20L:4D and 16L:8D); and light intensity (40 watts m-2, 60 watts m-2 and 80 watts m-2); also, a control treatment was set-up outside the greenhouse to receive the normal environmental condition. Light manipulations inside the greenhouse were able to sustain the water quality within the desirable level for tilapia cultured in tank; while control tanks shows high water quality variation. Growth performance of tilapia cultured in tank responds positively in prolonged photoperiod at different light intensities. However, light manipulation gave insignificant difference on feed conversion ratio and survival rate compared to normal condition. Results indicated that 20-hours photoperiod and 40 watts m-2 light intensity is just enough to sustain the recommended water quality and better growth performance of the cultured tilapia in indoor tank system. It can be concluded that longer photoperiod and restrained light intensity can improved the growth performance of tilapia under indoor tank culture.