Microplastics in Commercial Fish Feed in Bangladesh: An Emergent Risk Factor for Aquaculture

The rise of microplastics (MPs) as a significant environmental contaminant has raised concerns about their potential presence in aquatic ecosystems and food webs. The current study aimed to evaluate the properties and frequency of MPs in Bangladeshi commercial fish feed, a vital aquaculture sector component. Twenty-one commercial fish feed samples representing three distinct grades (starter, nursery, and grower) and seven commercial formulations were tested. Standard digestion, density separation, and filtering techniques were used to extract MPs. The findings demonstrated that all the samples had extensive MPs contamination, with an average concentration of 9.23–14.27 MPs per gram of feed. Grower feeds have the lowest frequency of MPs, while starter feeds show highest MP abundance. The most abundant forms were fibers (45.44%), followed by fragments (36.30%) and microbeads (18.26%). The most frequently occurring colors were black (33.30%), transparent (27.37%), and blue (13.63%). The most dominant group of MPs was <300 µm (52.36%). Polystyrene (PS) and ethylene–vinyl acetate (EVA) were found to be the predominant polymers, making up 32.12% and 23.85% of the total MPs, respectively, based on Attenuated Total Reflection Fourier Transform Infrared Spectroscopy. Nitrile butadiene rubber (NBR) indicated low hazard, while low-density polyethylene (LDPE) medium, polymethyl methacrylate (PMMA), polycarbonate (PC), and acrylonitrile butadiene styrene (ABS) indicated very high hazard. In addition, fish feed samples remained at low risk as specified by the Pollution Load Index (PLI). Given the possible dangers to fish health, human consumption, and environmental sustainability, this study emphasizes the urgent need for mitigation techniques to minimize MP contamination in aquafeeds.