Phytobiotics as promising antimicrobial agents in aquaculture health management

As aquaculture continues to expand as a major food-producing sector, reliance on synthetic antibiotics raises concerns related to antimicrobial resistance, public health, and environmental sustainability. In response, the present study explores plant essential oils (EOs) as eco-friendly alternatives to conventional antimicrobials. The phytochemical composition, the antioxidant potential, antibacterial activity, and antibiofilm properties of EOs derived from Origanum vulgare L., Vitex agnus-castus L. and Mentha longifolia (L.) Huds. were investigated against common fish-pathogenic bacteria. Additionally, cytotoxicity was assessed using Epithelioma papulosum cyprini (EPC) cells to determine safety. Among the tested oils, Origanum vulgare L. EO (OvEO) exhibited the strongest bioactivity, showing potent antioxidant effects, broad-spectrum bactericidal action at low concentrations, significant antibiofilm inhibition, and minimal cytotoxicity. Mentha longifolia (L.) Huds. EO (MlEO) displayed moderate bioactivity, followed by Vitex agnus-castus EO (VacEO). These findings suggest that the varying antimicrobial and antioxidant capacities are attributable to differences in phytochemical composition, highlighting OvEO as a promising natural candidate for sustainable disease management in aquaculture.