Microplastic ingestion affects the lateralised processing of predator stimuli in fish

Microplastic ingestion affects fish brains at the molecular level, but its impact on cognitive phenotype remains unclear. We fed zebrafish (Danio rerio) food containing either polyethylene or poly(butylene-adipate-co-terephthalate) microplastics for 20 days and assessed their lateralisation, which reflects how information processing is split between brain hemispheres. No changes appeared in rotational or mirror tests, but lateralisation was disrupted in the detour test when facing a predator model. These results suggest microplastic ingestion can impair specific cognitive traits at the phenotypic level.