Antimicrobial Resistance and Antibiotic Stewardship in Aquaculture

Why antimicrobial resistance matters in aquaculture, how it spreads under a One Health lens, and the WOAH and FAO prudent-use principles that reduce reliance on antibiotics.

Overview

Antimicrobial resistance (AMR) occurs when bacteria, viruses, parasites and fungi develop the ability to survive the drugs used to treat them, making infections harder to control. WOAH describes AMR as one of the greatest global health challenges of our time, associated with an estimated 5 million human deaths in 2019. In aquaculture, the way antimicrobials are used directly influences how quickly resistance develops and spreads.

Why it matters in aquaculture

FAO identifies the imprudent use of veterinary medicines in aquaculture as a contributing factor in the spread of antimicrobial resistance. Intensification of fish farming, poor or absent biosecurity, and indiscriminate drug use increase reliance on antimicrobials. Resistant bacteria and resistance genes can move between fish, water, sediment and people, which is why AMR is treated as a shared problem rather than a farm-only one.

The One Health connection

WOAH frames AMR through One Health, the recognition that animal, human and environmental health are intertwined and interdependent. WOAH works with FAO, WHO and UNEP in the Quadripartite partnership, noting that resistant bacteria spread across animal, human, plant and environmental populations and that a large share of human pathogens originate from animals. Antimicrobial use in aquaculture can therefore affect the effectiveness of the same drug classes in human medicine.

Prudent-use principles

1. Use antimicrobials responsibly and only when necessary; never use them against viral infections, and never as growth promoters (WOAH).
2. Diagnose first: confirm a bacterial cause before treating, and choose the correct drug, dose and duration.
3. Use only approved products and observe the withdrawal period for food fish.
4. Reduce the need for antimicrobials through good aquaculture practice, biosecurity and vaccination (FAO).
5. Keep treatment records and work under veterinary oversight.
6. Explore alternatives being studied, such as bacteriophages, probiotics and immunostimulants (FAO).

FAO supports countries through National Action Plans and the Progressive Management Pathway for AMR, and has helped many low- and middle-income countries implement these plans within a One Health approach.

Restricted and banned substances

Some antimicrobials and dyes are prohibited in food-producing fish because of human-health risks. The Merck Veterinary Manual states that compounds including chloramphenicol, nitrofurans, fluoroquinolones and quinolones, steroid hormones and malachite green should never be used in food animals for any reason. Using such substances, or ignoring withdrawal periods, can render seafood adulterated and subject to regulatory action.