The effects of essential oils and their major compounds on fish bacterial pathogens – a review

Summary The increased resistance of fish pathogens to conventional treatments has lead researchers to investigate the antibacterial properties of natural resources, such as essential oils ( EO s) of plants, in an effort to find products that are less harmful to the environment. The objective of this review is to provide an overview of the studies, in vivo and in vitro , that addressed the use of EO s and their major compounds as antimicrobial agents in fish, to identify the best EO s and compounds to investigate considering feasibility of application and suggest possible future studies. To date, studies suggest that the use of EO s in the prevention and/or treatment of infectious diseases in fish may be a promising strategy to reduce the use of conventional antibiotics in aquaculture, since several EO s effectively reduce or avoid the effects of bacterial infections in fish. The use of EO s through nanotechnology delivery systems, especially in dietary supplementation experiments, is promising. This form of application of the EO s allows a potentiation and targeting of the desired effect of the EO s and also allows the protection of EO s active constituents against enzymatic hydrolysis, deserving further study.