Variation of growth and proximate composition in Portunus pelagicus juveniles fed with selected feeds in recirculating aquaculture system (RAS)

Abstract

The experiment was conducted to determine the suitability of using scad fish, shrimp and common squid for the direct and indirect application as diets for the juvenile rearing of the blue swimming crab. A total of 54 crab juveniles with an initial weight of 2.46 ±0.94 g were randomly stocked in triplicate at 6 crabs per 60 l tank (0.26 m²) experimental units and fed twice daily with three different types of feed namely scad fish, squid tissue and frozen shrimp for a period of 31 days. At the end of the trail, ammonia and nitrite-nitrogen compound were significantly higher in shrimp fed group. It is found that final body weight (g) of was significantly higher when fed with squid, however no significant differences were noticed between scad fish and shrimp fed groups. The whole body proximate composition was similar in all the diet fed individuals except the level of lipid which was higher in squid compared to scad fish and shrimp. Significantly (p<0.05) better food conversion ratio (FCR) was observed in juvenile crab fed with squid even though scad fish possessed the highest crude protein of 83.33%. Overall, the results suggested that squid meal could be recommended for juvenile culture. Hence, squid meal may be incorporated in crab artificial diet as protein source to attain better survival and growth.