Prevalence of microplastics in commonly consumed fish species of the river Old Brahmaputra, Bangladesh

Microplastics (MPs) are pervasive in aquatic environments, but inland waterbodies (rivers and floodplains) have received much less attention. The present study assesses the incidence of MPs in the gastrointestinal tracts of five commercially important edible fish species-two column feeders (n = 30) and three benthivores (n = 45) from upstream, midstream, and downstream of the Old Brahmaputra river in north-central Bangladesh. MPs were detected in 58.93% of fish, with the highest level in freshwater eel, Mastacembelus armatus (10.31 ± 0.75/fish). Fibers (49.03%) and pellets (28.02%) were the most frequent MPs. Nearly 72% MPs were smaller than 1 mm, and 50.97% were black. FTIR analysis showed 59% polyethelene (PE), followed by polyamide (40%) and unidentified (1%). MP ingestion was linked to fish size and weight, and a high incidence was recorded in the downstream river. Two omnivorous benthic fish ingest more MPs than others. The results corroborate the presence of MPs in the inland river and fish fauna and augment our understanding of heterogeneous MP uptake by fish.