Microplastics in fish (including dried fish and small fish eaten whole)
Microplastics in fish are mainly found in the digestive tract (viscera). The viscera are usually removed before eating, but some studies found them in the flesh (muscle), and one study of dried fish found more in the flesh. In Japanese anchovy from Tokyo Bay, they were found in the digestive tracts of 77% of individuals.
Amounts found in studies
| Study | What was tested | Size range and method | Results |
|---|---|---|---|
| Tanaka & Takada (2016) | 64 Japanese anchovy from Tokyo Bay | Every particle identified by FTIR | From the digestive tracts of 49 fish (77%). Average of 2.3 particles per fish, maximum 15. Polyethylene 52.0%, polypropylene 43.3%. 80% were 0.15–1 mm |
| Yagi et al. (2022) | Commercial fish from waters around Kyushu | — (confirmed in the abstract) | Share with particles in the digestive tract: pelagic fish (150 fish) 39.1%, demersal fish (235 fish) 10.3% |
| Piyawardhana et al. (2022) | 14 dried fish products from 7 Asian countries | Micro-Raman | In most of them. About 80% were fibers. The highest was a Japanese dried round herring (urume iwashi) at 1.92 particles per fish (0.56 per g of dry weight) |
| Karami et al. (2017) | 4 types of dried fish (30 fish each) | — (confirmed in the abstract) | In 2 types, there were more in the flesh with the viscera removed than in the viscera |
| Barboza et al. (2020) | 150 wild fish from the North Atlantic | — (confirmed in the abstract) | In the dorsal flesh of 32% of the fish. Average of 0.054 particles per g |
Results can differ by orders of magnitude depending on the smallest particle size counted and whether particles are counted or weighed. Numbers from different studies cannot be compared directly (→ Why numbers differ).
Good to know
- Removing the viscera does not guarantee that the microplastics are gone (Karami 2017, Barboza 2020).
- The Tokyo Bay study examined the digestive tract contents of adult fish. It did not measure products such as niboshi (dried small sardines) or shirasu (whitebait).
- Particles resembling the microbeads used in face wash and similar products (7.3%) were also found. In Japan, the cosmetics industry decided in 2016 to voluntarily stop using them (→ Regulation and rules).
Data from Japan
There are studies of Japanese anchovy from Tokyo Bay (2016), commercial fish from waters around Kyushu (2022), and Japanese dried round herring (2022). We found no study that directly measured products such as niboshi, shirasu or chirimen.
Types of plastic found
Related explainers
Sources
- Tanaka K, Takada H. Sci Rep 2016;6:34351 (PMID 27686984)
- Yagi M, et al. Mar Pollut Bull 2022;174:113304 (PMID 35090289)
- Piyawardhana N, et al. J Hazard Mater 2022;423:127093 (PMID 34536847)
- Karami A, et al. Sci Rep 2017;7:5473 (PMID 28710445)
- Barboza LGA, et al. Sci Total Environ 2020;717:134625 (PMID 31836230)
Last checked 2026-10-01. “Confirmed in the abstract” means we report only what the paper's abstract says. This page is a translation of our Japanese page; if they differ, the Japanese page is the reference.