Impact of Dietary Formulation on the Gonadal Maturation and Reproductive Potential of the Broodstock Sandfish ( Holothuria scabra ) in Sea Cage Culture

The sustainable aquaculture of sandfish (Holothuria scabra), a high–value species prized for its nutritional and medicinal properties, depends on optimized broodstock management. This study investigated the impact of three dietary formulations—a commercial feed, a mix feed consisting of specifically selected ingredients (seaweed, polychaetes, and green caviar), and a mud feed—on the reproductive performance of H. scabra over six months. Results indicated that the mix feed significantly enhanced the gonadosomatic index (GSI = 0.55 ± 0.22%) and sperm viability compared to other groups (p < 0.05). Furthermore, this treatment elevated reproductive hormone levels (17β–estradiol and testosterone) and upregulated the expression of key genes, 17β–hydroxysteroid dehydrogenase and vitellogenin, by 1.8– and 2.1–fold, respectively. Histological analysis confirmed advanced gonadal maturation in % of the mix feed group. These findings demonstrate that nutritionally enriched feeds containing seaweed, polychaetes, and green caviar effectively promote gamete quality and maturation, offering a practical strategy for enhancing hatchery–based seed production. Overall, this study provides a circular, low-footprint nutritional strategy that minimizes reliance on resource-intensive commercial feeds by leveraging localized coastal bioresources. Optimizing broodstock conditioning through targeted endocrine and molecular up-regulation serves as a practical dietary framework for aquaculture to advance sustainable marine resource management, accelerating hatchery yields for ecological restocking and sustainable aquaculture development.