Culture of Soft Shell Mangrove Crab, Scylla Spp. Production in the Southwest Region of Bangladesh

Abstract

The experiment was conducted for a rearing for a period of 150 days from mid-September to mid-February 2017 in three earthen ponds with an installing of 9880 cages per hectare with an average depth of 1.0 meter. The experiment was designed at the ponds of Kaligonj Chingri Farm as a treatment T1, Allarchar chingri farm as a treatment T2 and Shamnagar private crab farm as a treatment T3. Before stocking crabs were categorized at five size groups. At stocking, all crabs were with an initial mean carapace width and weight of individual was recorded in three treatments. The average final weight of crab was recorded to be 180.56±4.08, 175.80±7.11 and 178.62±6.42 g in treatment T1, T2 and T3, respectively. The increase in weight of mud crab was the highest in T1 followed by T3 and T2. About five group of different crab weight was stocked in the cages of three treatments. Best SGR (1.67±0.01) and FCR (2.00±0.08) were recorded in treatment T1. The highest survival rate was also observed in T1 and the lowest survival rate was in T2. There was a significant variation (P<0.05) in the survival rate of crabs among three treatments. The net production of crab was at 5082.51, 4689.63 and 4923.48 kg/ha in treatment T1, T2 and T3, respectively. Highest production of soft shell crab was recorded in treatment T1. But no significant (P<0.05) different was recorded in treatment T1 and T3. But a significant (P>0.05) different was found between treatment T2 and treatment T1 and T3. Majority of the crabs about 60-70% molted during night than day time. As the crabs were increased in size, molt duration became longer from 17.0 to 26 days. Overall, highest growth, survival, production and net benefit of soft shell crab recorded at treatment T1. Therefore, treatment T1 and treatment T3 appeared to be most suitable for soft shell crab culture for availability of saline water and trash fish in this area.