Open Veterinary Journal, (2025), Vol. 15(7): 2921-2922

Letter to the Editor

10.5455/OVJ.2025.v15.i7.2

Addressing antimicrobial resistance in aquaculture globally

Krishna Prasad Acharya^1*, Sarita Phuyal² and Kailash Bohara³

¹Animal Disease Investigation and Control Division (ADICD), Department of Livestock Services (DLS), Lalitpur, Nepal

²Central Referral Veterinary Hospital (CRVH), Department of Livestock Services, Kathmandu, Nepal

³Department of Aquaculture and Fisheries, University of Arkansas at Pine Bluff, Pine Bluff, AR, USA

*Corresponding Author: Krishna Prasad Acharya. Animal Disease Investigation and Control Division (ADICD), Department of Livestock Services (DLS), Lalitpur, Nepal. Email: kpa26 [at] cantab.ac.uk

Submitted: 20/05/2025 Revised: 14/06/2025 Accepted: 15/06/2025 Published: 31/07/2025

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Aquatic animals account for up to 20% of the total animal protein in the human diet (Schar et al., 2021). These aquaculture species, including fish, serve as reservoirs for zoonotic pathogens that can infect humans either directly or through foodborne transmission. Common infections affecting fish handlers and consumers in aquaculture include Aeromonas hydrophilia, Mycobacterium marinum, Streptococcus iniae, Vibrio vulnificus, and Photobacterium damselae (Haenen et al., 2020). Additionally, commercial seafood products have been identified as carriers of zoonotic pathogens. Antibiotics are used for therapeutic and prophylactic purposes in aquaculture (Rodgers and Furones, 2009), resulting in prolonged and often irrational use of antibiotics in aquaculture systems, which aids in the development of antimicrobial resistance (AMR) in the aforementioned pathogens found in aquatic systems. These microbes not only resist antibiotics but also propagate genes that cause AMR, such as extended-spectrum beta-lactamases (Ramos et al., 2020). For instance, previous research on fish and eel aquaculture systems found that strains of Aeromonas harbored a large number of plasmids, integrons, and gene cassettes responsible for antibiotic resistance (Piotrowska and Popowska, 2014). The incidence of AMR in aquatic animals has increased over the last decade, raising concerns and emphasizing the critical need for comprehensive strategies to address AMR transmission in aquatic habitats, particularly in aquaculture practices. However, there is insufficient research to understand the situation of AMR in aquaculture systems, which may be one of the reasons why there is no or limited priority research on AMR in aquaculture systems. Antibiotic resistance is a growing concern in aquaculture because it can act as a genetic reactor or hotspot for AMR genes, allowing for significant genetic exchange and recombination, resulting in the emergence of extensively drug-resistant (XDR) and multidrug-resistant (MDR) strains (Algammal et al., 2022). The prolonged use of antibiotics in aquaculture increases selective pressure on bacterial populations, thus facilitating the development of AMR. In addition, the introduction of other antibiotic-related pharmaceutical products into aquaculture systems can further intensify AMR.

Aquaculture production and antibiotic use

Many countries have restricted the prophylactic use of antibiotics in aquaculture because of concerns about their potential health risks. For instance, the EU (Watts et al., 2017) has banned the use of antibiotics for non-therapeutic, or prophylactic purposes. However, developing and underdeveloped countries, which produce approximately 90% of global aquaculture production, lack regulations on the prophylactic use of antibiotics (Benbrook, 2002). Consequently, antibiotic usage is more prevalent in these regions. In top aquaculture-producing countries such as China, India, Indonesia, and Vietnam, antibiotic consumption accounts for over 93% of the total global antibiotic usage (Schar et al., 2020). Compared with antibiotics used in terrestrial farmed settings, antibiotics used in aquaculture settings are more likely to have effects due to their distribution through water.

In aquatic species, antibiotics are typically administered via feed, and residues can be found in both the fish body and the water through fecal matter and uneaten feed. Studies have indicated that nearly 80% of antibiotics given to aquatic species are released into the water (Rigos et al., 2004; Cabello et al., 2013), raising serious concerns about AMR for zoonotic bacterial species such as Aeromonas hydrophila, S. iniae, and Vibrio sp. Moreover, bacterial species like Escherichia coli, Shigella spp., and Legionella spp., which affect humans, also inhabit water bodies and are prone to AMR due to the extensive use of antimicrobial agents in aquaculture. Integrated fish farming, which is prevalent in Asian and African continents, intensifies AMR concerns. This system of farming involves the use of fertilizer and drainage from livestock and poultry to enhance algal growth and feed, thereby serving as a medium for transferring antibiotic residues from these animals to fish and water (Hoa et al., 2011). This practice has led to the emergence of AMR in ubiquitous bacterial species found in pond sediments, which are frequently overlooked but can harbor AMR genes capable of transferring to zoonotic species.

Moving forward

Addressing AMR in aquaculture is critical for protecting the environment, ensuring sustainable food production, and ultimately public health. Regulating antimicrobial use in aquaculture through the development of country-specific action plans is essential for major aquaculture-producing nations. These plans should include fundamental strategies such as regulating antibiotic use, implementing monitoring systems, conducting R&D initiatives, and raising public awareness regarding AMR. Research is crucial to gain a better understanding of the AMR situation in aquaculture systems and to devise and implement strategies based on these findings. These strategies aim to regulate antibiotic usage, promote responsible aquaculture practices, and mitigate the spread of AMR in aquatic environments. Additionally, it is important to explore novel technologies such as probiotics, prebiotics, and enzybiotics to enhance aquatic animal health and diversify treatment options. Given the complexity of AMR in aquaculture systems, a global One Health approach involving collaboration between human, animal, and environmental sectors is required to address the issue. This strategy must include legislation to establish antimicrobial use standards, capacity building to strengthen regulatory enforcement and healthcare practices, a robust surveillance system to monitor AMR, and educational initiatives to raise awareness, all of which necessitate an effective collaboration system to foster partnerships and knowledge exchange. Integrating these components will help reduce the potential risks and problems of AMR in aquaculture while also promoting the health and sustainability of aquatic ecosystems, food safety, and public health globally.

Conflicts of interest

None to declare.

Author’s contribution

All authors contributed equally.

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