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

The increased resistance of fish pathogens to conventional treatments has lead researchers to investigate the antibacterial properties of natural resources, such as essential oils (EOs) 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 EOs and their major compounds as antimicrobial agents in fish, to identify the best EOs and compounds to investigate considering feasibility of application and suggest possible future studies. To date, studies suggest that the use of EOs 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 EOs effectively reduce or avoid the effects of bacterial infections in fish. The use of EOs through nanotechnology delivery systems, especially in dietary supplementation experiments, is promising. This form of application of the EOs allows a potentiation and targeting of the desired effect of the EOs and also allows the protection of EOs active constituents against enzymatic hydrolysis, deserving further study.