The role of fish farming in the dissemination spread of antibiotic resistance genes (ARGs) has become an urgent environmental and public health concern. Fish farms, particularly those using intensive or semi-intensive aquaculture practices, serve as hotspots for the selection and proliferation of antibiotic-resistant bacteria (ARB). Labella et al. demonstrated a significantly higher incidence of multi-resistant bacterial strains in aquaculture centers (10%) compared to coastal areas (4%) in the Adriatic Sea​ [1]. Tetracycline resistance was particularly prominent, with up to 50% of bacterial isolates from specific zones, showing resistance., In contrast, resistance to flumequine remained low (0.3%), highlighting selective pressures imposed by antibiotic use patterns. Horizontal gene transfer, facilitated by mobile genetic elements, allows for the spread of ARGs among bacterial populations in fish farm effluents, sediments, and biofilms. Effluent water from aquaculture systems has been identified as a critical matrix contributing to ARG dissemination.

The frequent use of oxytetracycline, flumequine, and trimethoprim–sulfadiazine in fish farms exacerbates ARG selection. Studies have also shown cross-resistance, where exposure to older antibiotics like flumequine induces resistance to clinically relevant fluoroquinolones (e.g., ciprofloxacin), posing a direct threat to human health [2]. Furthermore, elevated water temperatures during summer were correlated with increased resistance incidence, suggesting environmental factors may amplify the selective pressures within aquaculture systems [2] .

This review highlights the role of aquaculture practices in driving antibiotic resistance, with fish farms acting as reservoirs for ARBs and ARGs.

[1] Labella, A., et al (2013). High incidence of antibiotic multi-resistant bacteria in coastal areas dedicated to fish farming.. Marine pollution bulletin, 70 1-2, 197-203 . https://doi.org/10.1016/j.marpolbul.2013.02.037.

[2] Jo, H., et al (2021). Fish farm effluents as a source of antibiotic resistance gene dissemination on Jeju Island, South Korea.. Environmental pollution, 276, 116764 . https://doi.org/10.1016/j.envpol.2021.116764.