Effect of dietary supplementation with Lamduan (Sphaerocoryne lefevrei (Baill.) D.M. Johnson & N.A. Murray) fruit powder on the growth, digestive enzymes, non-specific immune system, and skin pigmentation of Siamese fighting fish (Betta splendens Regan, 1910)

Various parts of Lamduan (Sphaerocoryne lefevrei (Baill.) D.M. Johnson & N.A. Murray) have long been utilized in traditional medicine to treat a range of human ailments. Nonetheless, its potential as a bioactive feed supplement in aquaculture production remains underexplored. This research assessed the impact of incorporating Lamduan fruit powder (LFP) into the diet on the growth performance, digestive enzymatic functions, mucosal immune activity, and pigmentation of Siamese fighting fish (Betta splendens Regan, 1910). A total of 300 juvenile male short-tail B. splendens (average initial weight: 0.08 ± 0.01 g; total length: 1.97 ± 0.01 cm; two-month-old) were assigned to four dietary treatments with three replicates each and fed experimental diets containing 0, 10, 30, and 50 g/kg of LFP for eight weeks. Results revealed that the group receiving 50 g/kg exhibited significantly enhanced growth metrics (p < 0.05), while parameters such as feed efficiency, survival rate, and viscerosomatic index remained statistically unchanged (p > 0.05). Enzyme-specific activities, including amylase, protease, and lipase, along with mucus-based immune markers such as total protein, IgM, anti-protease, myeloperoxidase, superoxide dismutase, catalase, and total protease, were markedly improved in fish fed LFP-enriched diets. Moreover, antioxidant capacity and carotenoid deposition in skin and muscle tissues were significantly elevated. Based on second-order polynomial regression, an LFP inclusion of 27.18–28.58 g/kg is recommended as a practical level to maximize pigmentation while maintaining acceptable growth. The findings highlight the potential of LFP as a functional dietary supplement to enhance both health status and coloration in ornamental fish