Fattening of mud crab (Scylla paramamosain) in a recirculating tank system with different salinities

Mud crab (Scylla paramamosain) is one of the important species for aquaculture. The experiment was conducted at Ca Mau Community College to develop a mud crab fattening process in a recirculating tank system and to diversify aquaculture models in the Mekong Delta. In this experiment, mud crabs were reared at different salinities of 5, 15, 25, and 35‰ with three replicates for each treatment. Early gravid female crabs were stocked at 20 individuals/m2 in 200 L tanks linked with biofilters. Mud crabs were fed with trash fish at 3% of body weight daily. After 33 days of rearing, the results showed that the survival rates of full-gravid crabs in the treatments with salinities of 5‰, 15‰, 25‰, and 35‰ were 54.3%, 64.8%, 95.8%, and 91.5%, respectively. The daily weight gain, specific growth rate & gonadosomatic index of crabs in treatments ranged from 0.51 - 0.60 g/day, 0.17 - 0.20%/day, and 7.67 - 8.87%, respectively. However, there were no significant differences in these parameters among treatments (P > 0.05). The ovary weight (from 19.33 to 28.67 g) and the ratio of weight of ovary to hepatopancreas (from 147.22 to 220.24%) of crabs among treatments increased significantly with culture time, but were not significantly different (P > 0.05). Generally, the present study revealed that mud crab fattening at the salinity of 25‰ gave the best profit. These findings significantly contribute to improving technical processes for fattening of mud crabs reared in recirculating systems.