Physiological and Nutritional Effects of Dietary Zanthoxylum acanthopodium Seed Supplementation on Growth Performance, Immune Response and Disease Resistance in Neolissochilu shexagonolepis (McClelland 1839).

This study investigated the nutritional potential of Zanthoxylum acanthopodium seed supplementation in enhancing growth, immunity, and disease resistance of Neolissochilus hexagonolepis (chocolate mahseer) against Saprolegnia parasitica infection. Juvenile fish (10.5 ± 0.3 g) were randomly distributed into 12 tanks representing four treatment groups in triplicate: control (basal diet) and three experimental groups fed diets supplemented with 0.5%, 1% or 2% Z. acanthopodium seed powder. The experiment comprised a 60-day feeding trial with sampling conducted at Days 0, 15, 30 and 60, followed by a 14-day pathogen challenge with sampling at Says 7 and 14 post-challenge. Data were analyzed using one-way ANOVA with Tukey's post hoc test and Kaplan-Meier survival analysis. Nutritional analysis revealed Z. acanthopodium seeds contained significant bioactive compounds including alkaloids (3.45 ± 0.28 mg/g), flavonoids (2.87 ± 0.19 mg/g), and terpenoids (4.12 ± 0.31 mg/g). The 1% supplementation level demonstrated optimal effects, significantly enhancing lysozyme activity (65.2% higher, p < 0.05), respiratory burst activity (84.2% higher, p < 0.05) and serum immunoglobulin levels (72.3% higher, p < 0.05) compared to control. Growth performance showed highest weight gain (241.0 ± 9.4%, p < 0.05) and specific growth rate (2.0 ± 0.1%/day, p < 0.05) in this group. Following S. parasitica challenge, the 1% group exhibited superior disease resistance with 86.67 ± 3.3% survival compared to 58.33 ± 4.4% in control (p < 0.05), while sham-challenged fish maintained 100% survival across all treatments. Molecular analysis confirmed significantly lower fungal loads in treated groups, with 1% treatment showing minimum fungal DNA copies (1.5 × 10⁶ copies/mg tissue) versus control (4.8 × 10⁶ copies/mg tissue, p < 0.05). These results establish Z. acanthopodium seed's efficacy as a sustainable nutritional supplement for improving fish health and productivity while reducing synthetic antimicrobial dependency in aquaculture.