Impact of Effective Probiotic Microorganisms (EPMs) on Growth Performance, Hematobiochemical Panel, Immuno-Antioxidant Status, and Gut Cultivable Microbiota in Striped Catfish (Pangasianodon hypophthalmus)

Striped catfish, Pangasianodon hypophthalmus, has recently emerged as a promising candidate for Egyptian aquaculture owing to its rapid growth; however, under intensive culture, it is vulnerable to Aeromonas hydrophila. The efficacy of dietary supplementation with effective probiotic microorganisms (EPMs) in enhancing growth performance, feed utilization, physiological health, and disease resistance of P. hypophthalmus against A. hydrophila challenge was evaluated. A 90-day feeding trial was conducted with 300 fish randomly distributed into four triplicate groups (25 fish per replicate) reared in 12 indoor fiberglass tanks: a control and three groups receiving EPMs at inclusion levels of 1.5%, 3%, and 4.5%. The results showed significant, dose-dependent improvements across all EPMs-supplemented groups in survival, growth rates, feed utilization, and hematological parameters (RBC, Hb, PCV, WBC, and lymphocytes). Dietary EPMs led to significant improvements (p ≤ 0.001) in digestive efficiency, protein and lipid metabolism, antioxidant enzyme activity, immune performance, and the ability of striped catfish to withstand A. hydrophila infection. Hepatobiliary enzyme activities (ALT, AST, and ALKP), glucose levels, lipid profile markers, and hepatic MDA exhibited a significant linear decrease (p ≤ 0.0001) with increasing EPMs levels. The gut microbial composition showed a dose-dependent increase in beneficial lactic acid bacteria (LAB) and a reduction in TAPC, pathogenic coliforms (TFCC), and Vibrio spp. (TVC). These results demonstrate the dose-dependent effects of EPMs on enhancing aquafeed efficiency, overall health, and innate immunity in striped catfish.