Nursery culture of mud crab, Scylla serrata, using different ratios of natural food to formulated feed

The effect of feeding different ratios of natural food to formulated feed on the production and profitability of Phases 1 and 2 of nursery culture (3 weeks per phase) of hatchery-produced crab Scylla serrata was investigated. The feeds consisted of: mussel meat (M) alone, formulated diet (FD) alone, and their combination at M:FD ratios of 5 : 95, 10 : 90, 15 : 85, 20 : 80, 25 : 75 and 30 : 70. The crabs were stocked randomly in 12-m2 net cages installed in the nursery pond at stocking density of 50 m-2 for Phase 1 and 10 m-2 for Phase 2. Crabs were fed three times daily at 0830, 1300 and 1630 h. Results showed that in both phases, the survival rate, body weight, carapace width, and feed conversion ratio of crabs fed M, FD, and combination at different ratios were not significantly different (p>0.05). Profitability was better in 15 M:85 FD or 20 M :80 FD (Phase 1) and 30 M:70 FD ratio (Phase 2). The use of complete formulated diet as feed for crabs reduced the reliance on wet natural food.