Prevalence, characteristics and risk assessment of microplastics in native freshwater fish species from Kaptai Lake, Bangladesh

Microplastics (MPs) are plastic particles less than 5 mm in size. They are persistent and hazardous pollutants in both marine and freshwater ecosystems worldwide with significant potential for bioaccumulation. As their occurrence in commonly consumed native fish species from Kaptai Lake, Bangladesh remains poorly understood, this study investigated the prevalence, characteristics, and risks of MPs in five native freshwater fish species from the lake: Gudusia chapra, Corica soborna, Mystus tengara, Amblypharyngodon mola, and Rohtee cotio from Kaptai Lake, Bangladesh. A total of 75 specimens (15 per species, 25 per location) were collected from Bangladesh Fisheries Development Corporation (BFDC) Fish Market, Reserve Bazar, and Shubholong Bazar in December 2024. MPs were detected in 100% of specimens, confirming widespread contamination. M. tengara exhibited the highest abundance (0.63 ± 0.09 items/g tissue; p < 0.05). Fibers (85%) dominated over fragments (15%), with sizes ranging from < 100 µm to 3000 µm, most frequently 151–500 µm. Blue, black, and white particles predominated, suggesting sources from fishing gear and consumer plastics. Polyethylene was the most common polymer (71%), followed by polyester (14%) and ethylene–propylene copolymers (15%). A significant negative correlation was observed between body weight and MP abundance (r = − 0.724, p < 0.001), indicating higher susceptibility in smaller-bodied fish. This study highlights the urgent need for better plastic waste management by demonstrating widespread MP contamination in freshwater fish, which provides crucial baseline data that highlight possible ecological and human health risks for communities reliant on Kaptai Lake.