Optimizing Soft-Shell Crab Production: Enhancing Molting Efficiency with Mulberry Leaf Extract via Immersion

Soft-shell crab production often faces challenges such as low molting rates and decreased product quality due to mutilation methods. Herbal alternatives have shown potential to improve molting and crab quality, although they are generally administered through injections or feed. This study aimed to identify a more efficient herbal application method for soft-shell crab production, using a Recirculating Aquaculture System (RAS). Three doses of mulberry extract (4, 8, and 12 ppm/kg crab) were applied via immersion, and control group received no extract. A total of 200 juvenile crabs (weighing 50–90 g) were used. Observations of epipodite retraction after 30 days revealed that most crabs reached the pre-molting phase, with the highest pre-molting rate observed at the 8 ppm/kg dose. The highest molting rate (27%) was recorded at the 8 ppm/kg dose, compared to the control group (17%), while the 12 ppm/kg dose resulted in the lowest molting rate (10%). The highest post-molting weight gain (40.5 ± 11.14 g) occurred at a dose of 4 ppm/kg, while a dose of 12 ppm/kg caused mortality, delayed molting, and weight loss. In conclusion, soaking in mulberry extract at an optimal dose of 4-8 ppm/kg can improve the efficiency of soft-shell crab cultivation technology.