Dietary Lycium barbarum polysaccharides improve growth performance, antioxidant status, and intestinal histomorphology in obscure puffer ( Takifugu obscurus )

Lycium barbarum polysaccharides (LBP) are bioactive compounds possessing potent immunomodulatory, antioxidant, and intestinal health-regulating properties. Although extensively applied in terrestrial livestock, their effects on aquaculture species remain underinvestigated. This study evaluated the impact of dietary LBP on growth performance and physiological responses in obscure puffer ( Takifugu obscurus ). A 56-day feeding trial was conducted using experimental diets containing 0 (control), 0.5, 1.0, 1.5, and 2.0 g/kg LBP. Dietary LBP supplementation significantly enhanced growth performance (P < 0.05). In the 1.0 g/kg (L2) group, intestinal fold length was significantly increased, hepatic activities of antioxidant enzymes—total superoxide dismutase (T-SOD) and catalase (CAT)—together with plasma activities of immune-related enzymes—alkaline phosphatase (AKP) and acid phosphatase (ACP)—were significantly elevated (P < 0.05). CAT activity reached its highest level in the L2 group, while hepatic malondialdehyde (MDA) was significantly reduced (P < 0.05). Furthermore, digestive enzyme activities, specifically lipase (LIP) and amylase (AMS), were significantly potentiated. Furthermore, dietary LBP altered the intestinal microbial community structure, with a reduced relative abundance of Pseudomonadota, which was lowest in the L2 group. Quadratic regression analysis of growth parameters indicated that the optimal dietary LBP requirement for T. obscurus was approximately 1.235 g/kg. These findings suggest that dietary LBP supplementation can enhance growth performance, antioxidant status, immune response, and intestinal morphology in T. obscurus and may help maintain intestinal microbial homeostasis, highlighting its potential as a functional feed additive in aquaculture.