Reproductive performance and offspring quality in mud crab (<i>Scylla paramamosain</i>) broodstock fed different diets

A 2-month feeding trial was conducted to evaluate the reproductive performance and offspring quality of mud crab (Scylla paramamosain) females fed either a mixture of fresh food items (squid, shrimp, trash fish and Artemia biomass) or two experimental diets developed for penaeids. Before test initiation, mud crab females with an average individual wet weight of 200-300 g were acclimated for 2-3 days and reared together in one concrete tank of 2.0 × 0.5 × 8 m until spawning. After spawning, the spent spawners were unilaterally eyestalk ablated and randomly divided (20 animals/treatment) over three tanks of the same size and subjected to the dietary treatments. Spent spawners were used to eliminate the effect of feeding history. There were only minor differences in reproductive performance between dietary treatments. No differences were observed in the duration of the latency period from eyestalk ablation to spawning. Fecundity was only marginally higher for the broodstock fed the control diet. Also egg quality seemed only slightly affected by the treatments. Egg hatching rates were slightly higher in crabs fed the formulated diets compared to those crabs fed the fresh diet. The only statistically significant difference (p < 0.05) observed however was in egg hatching rate between the control diet and diet A2. In contrast, the crabs fed the fresh diet produced stronger larvae as determined by a starvation test. We therefore conclude that artificial diets resulted in reproduction success comparable to the use of fresh food. The nutritional composition of the artificial diets could however be improved in order to produce larvae of optimal quality. Based on our research findings, the protein level and n-3 HUFA level in the diet warrants further investigation in this respect