Utilization of Plant-Derived Essential Oils as Natural Alternatives for Controlling Fish Pathogens: A Critical Review of Their Use Against Aeromonas hydrophila

Aeromonas hydrophila infection is typically linked to outbreaks of diseases and its pathogenicity seems to be connected to environmental stress in hosts whose immune systems are compromised. Fish diseases have long been treated using synthetic antibiotics, but there are environmental and health concerns regarding their use due to the development of bacterial resistance. It has been suggested that essential oils (EOs), which are alternative antibacterial agents, could be applied in the aquaculture industry. Their biodegradability, affordability, efficiency, and quick metabolism minimize the likelihood of them building up in bodily tissues and provoking bacterial resistance. EOs can directly influence bacteria, altering the lipid composition and structure of bacterial cell membranes, enhancing their permeability, and disrupting their structure. In addition, they can boost fish immunity and increase resistance to contagious bacteria. EOs can be incorporated into fish diets as nutritional additives and/or applied in baths. This review discusses the in vitro and in vivo methodologies used to study the effects of EOs on A. hydrophila and the results obtained so far, as well as perspectives for new studies.