Effect of Almond Terminalia Catappa leaf Extracts on Growth, Gut Morphometry, Immunocompetence and Resistance of Heterobranchus longifilis to Pseudomonas Aeruginosa

This work evaluated the outcome of dietary ethanol (EE) and aqueous (AE) extracts of Terminalia catappa (Tropical almond) on growth, survival, oxidative stress, and resistance of Heterobranchus longifilis (Bagrid catfish) fingerlings to Pseudomonas aeruginosa. Five diets with different concentrations of T. catappa extracts (AL1, 0.0% extract; AL2, 0.5% EE; AL3, 1.0% EE; AL4, 0.5% AE and AL5, 1.0% AE) were formulated. Triplicate groups of H. longifilis (3.82±0.05 g) were fed diets at 3% body weight twice daily for 70 days. Results indicated that EE were richer in bioactive compounds including total phenolics, tannins, alkaloids, and flavonoids compared to AE. However, ethanol extracts negatively impacted feed intake and growth performance, particularly at higher concentration. Fish fed with aqueous extracts exhibited improved growth, higher hematocrit values, and enhanced antioxidant enzyme activity. Survival rates were highest in fish fed with aqueous extracts, particularly at 1.0% concentration. Fish fed with aqueous extracts showed increased resistance to Pseudomonas aeruginosa challenge, as evidenced by the higher relative percentage survival (RPS). These findings suggest that Terminalia catappa aqueous extracts can positively influence growth, health, and disease resistance of Heterobranchus longifilis. The study highlights the importance of considering extraction solvent when using plant-based extracts in aquaculture feed.