Occurrence of plastics and their characterization in wild caught fish species (Labeo rohita, Wallago attu and Mystus tengara) of River Ganga (India) compared to a commercially cultured species (L. rohita).

Ganga River in India is one of the top 10 polluted rivers in the world, yet there is no information on the occurrence of plastics in its wild caught fishes compared to commercially farmed fish species. In the present study, wild fish specimens belonging to nine species were caught along the River Ganga from two locations in Patna (Bihar). Organs (gastrointestinal tract, liver, gills and muscles) of fishes were analyzed for the presence of plastics. Plastics were identified using a stereomicroscope, and polymer types were characterized through FTIR analysis. Out of the nine wild fish species, only three (Labeo rohita, Wallago attu and Mystus tengara) showed presence of plastics in them. In contrast, organs of only one commercial fish species (L. rohita) were analyzed as this was the only fish species commercially farmed and available in local fish market of Gaya (Bihar, India). Specimens of this farmed fish species were procured from selected outlets having their supply from Fish Farm of the Department of Fisheries, Government of Bihar. The average number of plastic particles per fish in wild caught and commercial fishes was found to be 2.5 ± 1.6 and 5.2 ± 2.5, respectively. Further, wild-caught fishes indicated highest presence of microplastics (78.5%), followed by mesoplastics (16.5%) and macroplastics (5.1%). In commercial fishes, presence of microplastics was much higher (99.6%). Fragments (83.5%) represented the prominent microplastic type found in wild-caught fishes while fibers (95.1%) were the major type in commercial fishes. Colored plastic particles (white and blue) were abundant. The column feeder fishes were more plastic contaminated than the bottom feeder fishes. The predominant microplastic polymer type in the Gangetic and farmed fish(es) was polyethylene and poly(ethylene-co-propylene), respectively. This study, for the first time ever, reports plastic pollution in wild fishes of River Ganga (India) compared to farmed species.