Pond culture of mud crab Scylla serrata (Forskal) fed formulated diet with or without vitamin and mineral supplements

Abstract

The effects of three diets (Diet 1 – with vitamin and mineral supplements, Diet 2 – without vitamin and mineral supplements, and Diet 3 – fish bycatch) and monosex culture (male or female) on the growth, survival, feed conversion ratio (FCR), and production of mud crab Scylla serrata were investigated using a 2 x 3 factorial experiment with three replicates per treatment. Juvenile mud crabs were stocked at 1.0·m^-2 in 150 m² ponds and reared for 156 days. Results showed no significant interaction between monosex culture and diets (P > 0.05) so that data were pooled by sex and dietary treatment. Mean final body weight of male crabs (427 g) was significantly higher (P < 0.05) than female crabs (400 g). However, crab carapace length (CL) and width (CW), specific growth rate (SGR), FCR, survival, and production were not significantly different (P > 0.05) between the two sexes. Regardless of sex, crabs fed fish bycatch (Diet 3) gave significantly higher (P < 0.05) mean body weight (435 g) than those fed Diet 2 (395 g). Mean final body weight (410 g) of crabs fed Diet 1 was not significantly different from those fed Diets 2 or 3. The CL and CW, SGR, FCR, survival, and production of mud crabs fed the three diets, however, were not significantly different (P > 0.05). The economic viability of using a diet without vitamin and mineral supplements was comparable to that of a complete diet having about the same cost of production and return on investment of 74 to 75%. The study shows that cost-effective formulated diet could be used as alternative feed for fish bycatch thus saving on feed and storage costs.