Effects of Dietary β‐Glucan on Growth Performance, Haematobiochemical Responses, and Stress‐Related Gene Expression in Stinging Catfish ( Heteropneustes fossilis )

The present study evaluated the consequences of dietary β‐glucan on growth, haematobiochemical parameters, and stress‐related gene expression in stinging catfish, Heteropneustes fossilis . A basal diet was supplemented with 0%, 0.05%, 0.1%, and 0.5% yeast β‐glucan and administered to fish at 7%–4% of body weight per day for 100 days. The experiment was conducted in 12 plastic tanks arranged into four treatments in triplicate, with 30 fingerlings stocked in each tank. Initial body weight did not differ significantly among the treatment groups ( p > 0.05). At the end of the trial, final weight, weight gain, specific growth rate (SGR), feed conversion ratio (FCR), protein efficiency ratio (PER), hepatosomatic index (HSI) and viscerosomatic index (VSI) showed no significant differences ( p > 0.05) among treatments. However, dietary β‐glucan supplementation significantly improved survival compared with the control group ( p < 0.05). Whole‐body proximate composition remained unaffected by the dietary treatments, except for crude protein content. Dietary supplementation with β‐glucan up to 0.1% significantly improved haematological parameters and reduced serum glucose, total cholesterol, triglyceride, alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels. Furthermore, dietary supplementation with 0.05% β‐glucan significantly increased the relative mRNA expression of superoxide dismutase 2 (SOD2) in the liver and kidney tissues, while 0.05–0.1% β‐glucan significantly increased the relative mRNA expression of heat shock protein 70 (HSP70) in both tissues compared with the control ( p < 0.05). These findings indicate that lower inclusion levels (0.05%–0.1%) modulated haematobiochemical parameters and the expression of genes associated with antioxidant defence and cellular stress responses in H. fossilis . Quadratic regression analysis yielded estimated inclusion levels of 0.178%–0.255%, which require further validation. Further studies incorporating additional dietary levels and functional immune assessments are needed to determine whether β‐glucan supplementation improves disease resistance in H. fossilis .