Immunomodulatory effect of Aegle marmelos leaf extract on freshwater fish Cyprinus carpio infected by bacterial pathogen Aeromonas hydrophila.

Context: Aquatic organisms (especially fish) require potent defense mechanisms to protect themselves against pathogen invasion and disease formation. The use of immunostimulants in fish culture can prevent the diseases through augmentation of both specific and non-specific immunity.

Objective: A study was conducted to investigate the efficacy of different dietary doses of Aegle marmelos (Linn.