Organ-Specific Microplastic Profiling and Polymer Characterization in Freshwater Fish Species of Karnataka

Microplastic (MP) contamination is an emerging threat to freshwater ecosystems and food security. The objective of this study was to provide a comprehensive baseline assessment of MP abundance, polymer composition, and tissue-specific distribution across five organs (gut, gills, liver, gonads, and muscle) of two economically vital species Labeo rohita and Pangasius pangasius, in Udupi, Karnataka, India. MPs were detected in 100% of specimens, with higher mean (± standard deviation) abundances of 58.27 ± 10.48 particles per individual (particles ind^-1) in L. rohita and 42.40 ± 5.40 particles ind^-1 in P. pangasius. While L. rohita showed preferential accumulation in the gills and gut, in P. pangasius, MPs were more uniformly distributed across organs. Fibers dominated the assemblage (97.68%), with polypropylene and polyester identified as the primary polymers via Fourier transform infrared spectroscopy with attenuated total reflectance (FTIR-ATR) analysis. We conclude that the pervasive presence of MPs across all tissues, particularly the high accumulation in edible muscle and reproductive gonadal tissue, signals an urgent ecological risk and a direct pathway for human dietary exposure. The detection of MPs in gonadal tissues, while not yet linked to observed physiological impairment, identifies a potential reproductive risk and highlights a critical area for future histological and toxicological investigation. These findings establish a baseline for assessing the long-term health of local fisheries.