The present study investigated the effects of dietary supplementation with Gamnui (Gnetum montanum) extract on growth performance, immune response, and disease resistance in striped catfish (Pangasianodon hypophthalmus). Four experimental diets were formulated by adding Gamnui extract at 0 (G0), 2 (G2), 5 (G5), and 10 g kg-1 feed (G10), and administered to juvenile fish for six weeks. Growth parameters including final weight, weight gain, daily weight gain (DWG), specific growth rate (SGR), and feed conversion ratio (FCR) were recorded, along with relative internal organ indices. Post-feeding, fish were challenged with Aeromonas veronii to assess cumulative mortality and immune-related parameters. The results indicated no significant differences among dietary treatments in terms of final weight, weight gain, specific growth rate, or feed conversion ratio. Similarly, hepatosomatic (HSI), viscerosomatic (VSI), and gut indices (GSI) were unaffected. After bacterial challenge, the G10 group exhibited the lowest cumulative mortality, compared to the control (G0). Dietary Gamnui extract modulated several immune-related indicators: myeloperoxidase (MPO) activity increased consistently in fish receiving 10 g kg-1, while glutathione (GSH) levels were elevated across all supplemented groups, indicating enhanced antioxidant capacity. Peroxidase activity exhibited a treatment-dependent response after infection, whereas lysozyme activity did not change.. In summary, dietary Gamnui extract did not influence fish growth performance but enhanced non-specific immune responses and disease resistance, particularly at 10 g kg-1. These findings highlight the potential of this medicinal plant extract as a sustainable immunostimulant in aquafeed for striped catfish.
