New Insights into the Effects of Polystyrene Microplastics on Freshwater Fish, Labeo rohita: Assessment on Histopathology, Mineral Composition, Bioaccumulation and Antioxidant Activity

Microplastics (MPs) have become a pressing concern due to their pervasive presence in the environment and bioaccumulation in fish organs, potentially threatening ecosystem health. This study examined the impact of polystyrene (PS) MPs on Labeo rohita fingerlings (7.15 ± 0.02 g/fish) by exploring histopathological changes in intestine, altered mineral composition in muscles, bioaccumulation and modulated antioxidant enzyme activity. This study utilized six test diets comprising sunflower meal with varying polystyrene microplastic (PS-MP) levels. The control diet (I) contained 0% PS-MPs, while diets II-VI had 0.5%, 1%, 1.5%, 2%, and 2.5% PS-MPs, respectively, over a 90-day feeding trial. The fish were fed their respective test diets twice daily with a feeding rate of 5% wet body weight per day. The findings elucidated that the antioxidant enzyme activity and bioaccumulation were substantially altered by increased PS-MPs exposure. Moreover, histopathology examination revealed intestinal structural abnormalities, which worsened with escalating PS-MPs concentrations. Notably, test diet VI (2.5% PS-MPs) showed lower mineral content (P < 0.05) in fingerlings muscles when compared with control. In conclusion, results indicate that PS-MPs may negatively impact the L. rohita fingerlings, affecting histopathology of intestine, mineral composition, bioaccumulation, and antioxidant enzyme function.