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Global antibiotic use in fish farming

Global trends in antimicrobial use in aquaculture.

Overview

Schar D et al.. Sci Rep 2020 · PMID 33318576 · DOI 10.1038/s41598-020-78849-3

About 10,000 tonnes were used in 2017, mostly in Asia; salmon had the lowest use per kg.

Does the study support the specific claim? Yes · Methodological quality: moderate

Original publication

Plain-language summary

Study explained simply

What did the researchers want to find out?: Estimate use.
How was the study done?: Review + model.
How many people, animals or samples were studied?: 146 use rates from 25 surveys in 12 countries.
What was actually found?: About 10,259 tonnes in 2017 (uncertainty 3,163-44,727), rising to about 13,600 tonnes by 2030; 94% in Asia-Pacific; nearly all drugs medically important.
How large was the observed effect?: Salmon 27 vs catfish 157 mg/kg.
What do the results mean in everyday life?: Use varies by fish and country.
What are the study's limitations?: Very uncertain; few surveys; China and carp under-represented; Egypt not covered.
What does it say about Elawady's specific claim?: Supports, with nuance.
Do the results apply to Germany and Europe?: Moderate.
What can explicitly not be concluded from this study?: Human harm, residues in fish, or how much reaches the environment.

Scientific in-depth review

1. Full reference

Authors: Schar D et al.
Journal: Sci Rep
Year: 2020
Identifier: PMID 33318576 DOI 10.1038/s41598-020-78849-3
Verification: verified – PubMed efetch 2026-10-25
Retracted: no
Corrections: none
Extent checked: full text
Conflicts of interest and funding: Funding: Swiss National Science Foundation and Branco Weiss Foundation (TPVB); NSF grant CCF-1918628 and US CDC grant 16IPA16092427 (RL). Authors declare no competing interests.

2. Research question

How much antimicrobial is used in aquaculture globally (2017, 2030)?

3. Study design and population

Study design: Systematic review – Systematic review of antimicrobial-use point prevalence surveys in aquaculture (2000-2019, peer-reviewed and grey literature, incl. Chinese CNKI) combined with a projection model applying species-specific use coefficients to OECD/FAO and FAO FishStat production data
Population: Aquaculture species groups
Country: Global
Period: 2017 and 2030 projection
Sample size: 25 studies from 12 countries yielding 146 biomass-adjusted use rates (5 outlier rates omitted after sensitivity analysis); production data for 33 countries, EU-28 and 232 countries/territories in 6 regions
Inclusion and exclusion criteria: Point prevalence surveys reporting antimicrobial use in aquaculture 2000-2019; molluscs excluded; 96.5% of surveys from high- and upper-middle-income countries

4. Methods and endpoints

Exposure / intervention: Species group, country production
Comparator: Terrestrial animals, humans
Endpoints: Antimicrobial use (tons; mg/kg)
Statistical methods: Mean of log10-transformed use rates per species group with t-based 95% UIs, back-transformed; leave-one-out sensitivity analysis; ANOVA for production-system intensity (P=0.543, no association)

5. Actual results

Results: Global aquaculture antimicrobial use 10,259 t in 2017 (95% UI 3,163-44,727), projected 13,600 t in 2030 (4,193-59,295; +33%). Asia-Pacific 93.8%; China 57.9%, India 11.3%, Indonesia 8.6%, Vietnam 5%; Africa 2.3%, Europe 1.8% (2017). Use intensity: pooled group 208 mg/kg (70-622), catfish 157 (9-2,751), trout 103 (5-1,951), tilapia 59 (21-169), shrimp 46 (10-224), salmon 27 (17-41). Most-used classes: quinolones 27%, tetracyclines 20%, amphenicols 18%, sulfonamides 14%; WHO critically and highly important antimicrobials 35% and 61% of use. Aquaculture intensity 164.8 mg/kg in 2017, 79% higher than humans (92.2) and 18% higher than terrestrial food animals (140); aquaculture 5.7% of total 2030 use (236,757 t, UI 145,525-421,426). The study does not quantify how much antimicrobial reaches the environment.
Absolute risks: not reported
Authors' conclusion: Aquaculture antimicrobial use is projected to rise 33% by 2030, concentrated in Asia, with intensity exceeding human and terrestrial-animal use for some species; urgent need for surveillance and stewardship. Estimates are highly uncertain and may be conservative.

6. Strengths

First global quantitative estimate with explicit uncertainty
Systematic search including grey and Chinese-language literature
Sensitivity analysis for outliers
Transparent limitations

7. Weaknesses

Only 25 surveys from 12 countries; China and carp under-represented
Extremely wide UIs (e.g. catfish 9-2,751 mg/kg)
Assumes constant use coefficients 2017-2030
Surveys mainly from higher-income countries; point-in-time surveys may miss cumulative use (likely underestimates)
Pooled category (84.1% of use) mixes 12 species
No country data for Egypt; no data on residues or environmental fate

8. Risk of bias

Orienting tool: No standard tool fits (systematic review of use surveys plus projection model); structured validity judgement with AMSTAR 2-type considerations
Type of assessment: structured assessment based on the full text by a single reviewer (no formal double review)
Full formal assessment: no
Overall risk of bias: some concerns
Rationale: Single-reviewer structured judgement based on the full text; not formal (needs two independent reviewers).

8. Risk of bias
Domain	Judgement	Rationale
Search and selection	some concerns	Multi-language search including grey literature, but no protocol registration or duplicate screening reported; few eligible surveys.
Primary data quality	high	Heterogeneous point prevalence surveys of variable quality, not formally appraised; under-representation of main producer (China).
Model assumptions	some concerns	Constant coefficients, species mapping to a pooled group, production projections.
Uncertainty handling	low	UIs reported throughout; sensitivity analysis.

Full-text review (25 October 2026): Added search details (25 surveys, 12 countries), class distribution, WHO importance shares, intensity vs human/terrestrial, assumptions and author-stated limitations, funding; noted no data on environmental fate (80% figure absent); structured validity domains (overall unchanged).

9. Assessment of the statistical interpretation

Very wide uncertainty intervals (2017 total 3,163-44,727 t) mean the point estimate is only an order-of-magnitude guide; species comparisons (salmon 27 vs catfish 157 mg/kg) overlap heavily except for salmon's narrow UI.

10. Relevance to the specific claim

C-FSH-08.

11. Independent contrary findings

12. Transferability to Germany and Europe

Moderate (EU use low; salmon lowest intensity).

13. Overall methodological judgement

Best available global quantification: aquaculture uses substantial amounts of medically important antimicrobials, mainly in Asia, with high per-kg intensity; salmon has the lowest use intensity. Supports the 'large quantities' part of C-FSH-08 but provides no evidence for the '80% enter the environment with activity intact' figure.

Multidimensional assessment
Multidimensional assessment
Authenticity of the source	verified
Methodological quality	moderate
Risk of bias	some concerns
Precision of results	low
Directness	direct
Reproducibility	unknown
Consistency with the overall evidence	unknown
Regional transferability	moderate
Adequacy of the interpretation (by the archive)	not applicable

14. Open questions

Country-level data for Egypt and Africa; environmental fate of aquaculture antimicrobials; temporal trends in use coefficients.

15. Linked fact checks

Aquaculture uses vast quantities of antibiotics; about 80% enter the environment with their activity intact and select for resistance genes that can reach human pathogens. – Studies supporting the claim