Effects of dietary melatonin on male Sartoriana spinigera: Growth, blood profile, and histomorphology

Understanding male reproductive development in freshwater crabs is essential for advancing reproductive biology and sustainable aquaculture. This study evaluated the effects of dietary melatonin (MLT) on growth, moulting, and testicular development in Sartoriana spinigera over 28 days. Crabs were fed one of four diets: a control (0 MLT) and three MLT-supplemented diets at 35 mg/kg (T1), 70 mg/kg (T2), and 140 mg/kg (T3), with three replicates per treatment. Sixty crabs were distributed across 12 tanks and fed daily at 3 % body weight. Key parameters measured included gonadosomatic index (GSI), hepatopancreatic index (HPI), specific growth rate (SGR), Brix index, testosterone, lipid profile, and immune markers. T1 significantly enhanced GSI (3.58 ± 0.46), SGR % (1.041 ± 0.12), testosterone (0.86±0.01 ng/ml), and Brix index (14.62 ± 0.84) compared to the control, while higher MLT doses showed diminishing effects. HPI remained unchanged across treatments. Lipid profiles improved with MLT, notably increasing HDL, cholesterol, and triglycerides, while LDL decreased. Histological analysis revealed no hepatopancreatic abnormalities, and testicular development was most advanced in T1, with progressed germ cell stages covering 52 % spermatids. Principal component analysis confirmed enhanced reproductive and growth performance in T1. These findings suggest that dietary melatonin (35 mg/kg feed) supplementation may enhance growth performance and reproductive function, with particular benefits for testicular health and hepatopancreatic tissue integrity in S. spinigera , supporting its potential use in aquaculture and crustacean aquaculture practice. However, long-term studies with actual pond conditions are recommended to evaluate sustained effects, optimal dosing strategies, and potential impacts on fertility.