The low survival rate during hatchery stages is a major bottleneck in the seed production of mud crab (Scylla paramamosain). This study investigated the effects of enriching Artemia nauplii with varying doses of β-glucan on the growth performance, metamorphosis, digestive enzyme activities, and survival rates of mud crab larvae. The experiment was structured into five distinct dietary treatments containing different β-glucan concentrations including T1: 0 g L-1 (control), T2: 0.25 g L-1, T3: 0.5 g L-1, T4: 0.75 g L-1, and T5: 1 g L-1, administered during the zoea 3 to zoea 5 stages. The experimental results revealed that environmental water quality parameters, total bacterial counts, and Vibrio densities remained stable and within optimal thresholds across all treatment groups. While β-glucan enrichment did not significantly impact larval metamorphosis rates, developmental stage indexes, or the total length growth of the crab 1 stage, it noticeably influenced larval digestive physiology. Dietary supplementation enhanced the specific activities of proteolytic enzymes, specifically trypsin and pepsin, as well as lipase, while significantly decreasing amylase activity. Crucially, larval survival rate megalopa from the zoea 4 stage onward and overall crablet productivity were significantly enhanced in the 0.5 g L-1 and 0.75 g L-1 treatment groups compared to the control. The highest survival rate at crab 1 (6.8%) and peak crablet productivity (27,200 individuals m-3) were achieved in the group enriched with 0.5 g L-1 of β-glucan. These findings suggest that incorporating β-glucan as a nutritional supplement into standard larviculture protocols optimizes nutrient utilization and boosts physiological resilience.
