Study of Mud Crab Fattening in Earthen Pen Pond with Different Stocking Density

The effect of stocking densities on the growth, survival and production of mud crab (Scylla spp.) was tested in a pen culture rearing system. The experiment was conducted for a rearing period of 90days in nine earthen pen culture ponds having an area of 1052 m2 with an average depth of 0.98±0.14 m each. Mud crabs stocked at the rate of 0.02, 0.03 and 0.04 million.ha-1 were designated as treatment T1, T2 and T3. At stocking, all crabs were with an initial mean carapace length, carapace width and weight of individual was recorded in three treatments. Highest mean carapace length, carapace width and weight gain was documented 6.60±0.51cm, 12.11±1.88cm and 330.62±7.26 g in treatment T1 and lowest mean carapace length, carapace width and weight gain 6.18±0.36 cm, 10.02±2.28 cm and 252.52±3.44g was in treatment T3. Survival of individual followed the same trends as weight gain. Mud crab in treatment T1 created significantly higher specific growth rate than treatment T2 and T3. Feed conversion ratio was significantly lowest in treatment T1 followed by treatment T2 and T3 in that order. In despite of this, consistently higher net benefits were found from treatment T1 than from treatment T3 and T2 and also significant (P<0.05). Overall, highest growth, survival, production and net benefit of mud crab were recorded at a stocking density of 0.02 million individual.ha-1. Therefore, of the three stocking densities, 0.020 million individual. ha-1 appears to be most suitable stocking density for rearing of mud crab in earthen pen in pond culture system.