Haemato-Immunological Modulation in Pangasianodon hypophthalmus (Sauvage, 1878) Fingerlings Fed Syzygium cumini Leaf Powder

This study evaluated the nutraceutical efficacy of dietary jamun leaf powder on haematological responses, biochemical activities, immune competence, and oxidative stress-related responses in Pangasianodon hypophthalmus fingerlings, followed by a challenge study with Aeromonas hydrophila. The experimental fish were allocated to five dietary treatments, each with three replicates, and fed diets containing 0, 0.5, 1.0, 1.5, and 2.0% jamun (Syzygium cumini) leaf powder for 60 days. After the 60-day feeding trial, haematological, biochemical, antioxidant, and immune parameters were assessed before and after the challenge test. In the pre-challenge condition, fish receiving 1% (T2) exhibited significantly higher red blood cell (RBC) count, haemoglobin concentration, packed cell volume, serum protein levels, albumin, and globulin than the control (p < 0.05). Following A. hydrophila challenge, all parameters showed significant alterations compared with pre-challenge values (p < 0.05). Stress related metabolites, including glucose, cholesterol, and triglyceride levels, were significantly higher in the control group after the challenge (p < 0.05), indicating stress. Antioxidant enzyme activities, including superoxide dismutase (SOD) and catalase (CAT), were significantly higher in the 1% (T2) group during pre-challenge conditions. In contrast, hepatic enzyme activities were significantly elevated in the post-challenge control group (p < 0.05). Post-challenge immune parameters, including respiratory burst activity, lysozyme activity, and myeloperoxidase activity, were significantly higher in fish fed 1% leaf powder (T2) (p < 0.05). Overall, the inclusion of 1% jamun leaf powder in the diet improved haematological and biochemical status, antioxidant capacity, and immune responses, indicating its potential as an effective phytogenic feed additive for sustainable aquaculture.