Effects of Different Diets on Growth Performance and Nutritional Composition of Blue Crab (Callinectes sapidus, Rathbun, 1896) in a Recirculating Aquaculture System

This study evaluated the effects of three feeding regimens-commercial feed (CF), minced trash fish (MTF), and a 50:50 mixture (MIX)-on the growth performance and tissue composition of the blue crab (<i>Callinectes sapidus</i>) reared in a recirculating aquaculture system (RAS). A total of 96 crabs (8 per tank, four tanks per group) were fed daily at 3% of body weight. Growth was assessed via weight gain, carapace width (CW), and carapace length (CL), while biochemical analyses focused on lipid, fatty acid, and amino acid profiles. The CF and MIX groups exhibited significantly higher final body weights (115.64 ± 3.03 g and 113.53 ± 2.53 g, respectively) and CW (97.88 ± 1.02 mm and 97.16 ± 0.43 mm) compared to the MTF group (<i>p</i> < 0.05), suggesting more frequent or complete molting. The MTF group showed limited growth (102.81 ± 2.25 g; 95.24 ± 1.19 mm), likely due to reduced ecdysis events. Tissue lipid and fatty acid profiles reflected dietary inputs, with significant differences in DHA/EPA and n-3/n-6 ratios among treatments (<i>p</i> < 0.05). Essential amino acid levels decreased across all groups, possibly due to the metabolic demands of molting. These findings highlight the critical role of diet in promoting molting and improving tissue quality in blue crab aquaculture under controlled RAS conditions.