Evaluating the Impact of Dietary and Water-Based Probiotics on Tilapia Health and Resistance to Aeromonas hydrophila.

Aquaculture plays a critical role in global seafood production. Probiotics in aquaculture have gained popularity for enhancing fish health, growth, and water quality. This study aimed to evaluate the effects of probiotic supplementation through different methods-feed and/or water-on Nile tilapia's growth, health, and resistance to Aeromonas hydrophila. A total of 270 Nile tilapia fingerlings (initial weight 10 ± 05 g) were randomly divided into four experimental groups: (1) control group (basal diet with no probiotics), (2) feed additive group (basal diet + probiotics in feed), (3) water additive group (basal diet + probiotics in water), and (4) combined feed and water additive group (basal diet + probiotics in both feed and water). The trial lasted for 12 weeks. The study assessed water quality, growth performance, feed efficiency, digestive enzyme activities, intestinal morphometry, biochemical and immunological parameters, oxidative status, and resistance to A. hydrophila. The results revealed significant improvements in water quality (reduction in TAN and NH3), growth performance, feed utilization, digestive enzyme activity (amylase, lipase), and immune responses in all probiotic-treated groups compared to the control. The group receiving probiotics in both feed and water showed the highest growth, survival rate, and immune function improvements. Additionally, gene expression analysis revealed upregulation of immune-related cytokines (IL-1β, TGF-β, TNF-α) in this group. In conclusion, administering probiotics via both feed and water significantly enhances Nile tilapia's health, growth, and resistance to bacterial infections, with the combined approach yielding the best results. This study highlights the importance of optimizing probiotic administration methods to maximize benefits in aquaculture systems.