Potential impact of Lagenaria siceraria fruit powder on growth, blood biochemistry, antioxidant ability, immunity, proinflammatory cytokines expression, histoarchitectural traits, and resistance against Enterococcus faecalis in hybrid red tilapia fingerlings

This study evaluated the effects of supplementing fish diets with bottle gourd ( Lagenaria siceraria ) fruit powder on growth rates, blood biochemistry, antioxidant activity, immune response, and bacterial resistance in red tilapia fish. Red tilapia fingerlings averaging 44.0 ± 0.1 g were divided into four groups (Control, LS2, LS4, and LS6). Over 70 days, LS2, LS4, and LS6 were fed diets containing 2, 4, and 6 g/kg of L. siceraria fruit powder, respectively, while the control received a basal diet without supplementation. Growth parameters and crude protein content improved with increasing doses of L. siceraria fruit in diets. Feeding L. siceraria at all doses significantly increased serum biomarkers, including lysozyme, phagocytic activity, white blood cell (WBC) counts, superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GPx), total protein, albumin, globulin, and digestive enzyme activities. Conversely, levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and alkaline phosphatase (ALP) decreased significantly. A marked improvement was noticed in intestinal structure, with elongated, branched villi, and a maintained liver structure with minimal hepatocyte vacuolation. Dietary L. siceraria increased hepatic mRNA expression of proinflammatory cytokines (Il-1β and IL-8) and antioxidant genes (SOD, CAT, and GPx), which were upregulated. The LS6 group exhibited the most significant effects across nearly all parameters. Finally, the relative percent survival (RSP) in fish fed 0, 2, 4, and 6 g/kg L. siceraria during pathogen challenge was 37 %, 60 %, 68 %, and 81 %, respectively. In conclusion, 6 g/kg of L. siceraria improved growth efficiency, tissue health, and overall fish health, demonstrating its potential as a sustainable dietary supplement in aquaculture.