Eco Toxicological Assessment of Micro Plastic Ingestion in Freshwater Fishes: A Case Study on Bioaccumulation and Histopathological Alterations

Abstract

Microplastic pollution has emerged as a significant ecological threat in freshwater ecosystems, yet its biological impacts on aquatic fauna remain underexplored. This study aimed to assess microplastic bioaccumulation and associated histopathological alterations in three economically important freshwater fish species (Oreochromis niloticus, Labeo rohita, and Catla catla) collected from a major riverine system. Specimens were analyzed for gastrointestinal microplastic content using digestion and FTIR spectroscopy, and organ-specific accumulation (intestines, liver, gills) was quantified. Histopathological examinations were performed on formalin-fixed tissues using hematoxylin and eosin staining.Microplastics were detected in 87% of all sampled fish, with O. niloticus showing the highest mean burden (14.6 ± 3.2 particles/fish). Fibers were the most prevalent particle type, and polyethylene and polypropylene were the dominant polymers. Translocation of microplastics to liver and gill tissues was observed, indicating systemic distribution. Significant histological lesions were identified, including epithelial erosion, hepatocyte vacuolation, and gill lamellar fusion, with damage severity positively correlated to microplastic load (r = 0.78, p < 0.01). These findings underscore the potential of freshwater fish as bioindicators for microplastic pollution and highlight the physiological stress posed by chronic microplastic exposure.