Medicinal plants offer effective substitute to chemotherapeutic agents, particularly antibiotics. The study was conducted to evaluate the antibacterial efficacy of ethanolic extract of Allium sativum (A. sativum) against Aeromonas hydrophila (A. hydrophila) infection in Labeo rohita (L. rohita). Three different concentrations of A. sativum, 4 g/kg, 8 g/kg, and 12 g/kg were employed against A. hydrophila challenge. Fish (30±5g) were divided into six groups; Control, A. hydrophila challenged, A. hydrophila + A. sativum (4 g/kg), A. hydrophila + A. sativum (8 g/kg), A. hydrophila + A. sativum (12 g/kg) and A. hydrophila + Erythromycin. Herbal supplements were given for 14 days and sampling was performed 7 and 14 dpi (days post infection). Significant variations among hematological, biochemical and immune activities were observed between control and treated groups. When compared within the challenged groups, pathological symptoms were lessened in the A. hydrophila challenged+extract treated groups than the untreated infected fish. Interestingly, medium and high concentrations (8g/kg and 12g/kg) were effective to combat bacterial challenge. Moreover, after infection better fish survival was noted in extract treated groups as compared to untreated groups. Our study presents that herbal supplementation boosts-up fish immune system for better disease resistance against infection.

Index Terms- Allium sativum, antibacterial activity, characterizations, ethanolic extract, herbal supplementation, immune response