Dietary Matrine Supplementation Enhances Growth, Immunity and Disease Resistance in Nile Tilapia (Oreochromis niloticus)

Matrine, a bioactive alkaloid from Sophora flavescens, has gained attention as a phytogenic additive due to its antioxidant and immunomodulatory properties. Nevertheless, Nile tilapia (Oreochromis niloticus) is highly vulnerable to Streptococcus agalactiae infection under intensive aquaculture, leading to immune dysfunction and economic losses. This study aimed to evaluate the potential application of dietary matrine supplementation in enhancing tilapia health, growth performance, and resistance to bacterial infection. Fish were randomly assigned to four dietary treatments: control, 0.1% matrine (low dose), 0.5% matrine (medium dose), and 1.0% matrine (high dose). Blood, liver, spleen, intestine, head kidney, and muscle were sampled on days 0, week 4, and week 8 for growth, immune, and oxidative stress analyses. Subsequently, fish were challenged with S. agalactiae to evaluate immune gene expression and liver histopathology across groups. The results showed that dietary matrine supplementation significantly improved growth performance and feed conversion efficiency, enhanced nonspecific immune responses, and increased antioxidant enzyme activities. Moreover, 0.5% and 1.0% matrine markedly reduced mortality and hepatic injury after bacterial challenge. These findings indicate that matrine acts as an effective natural immunomodulator and may contribute to hepato-intestinal health, and dietary supplementation at 1.0% represents the relatively favorable inclusion level under the present conditions for improving health status and supporting sustainable Nile tilapia aquaculture.