Properties and abundance of microplastics found in fish feed, tissues, and culture water of catfish (Heteropneustes fossilis)

Microplastics are threatening to public and environmental health for their potential toxicity. Thus, understanding the ecological occurrence of MPs is crucial, but research on MPs in Bangladesh has yet in its infancy. To understand the existence of MPs in aquaculture, we investigated fish flesh, commercial fish feed, and rearing water of Heteropneustes fossilis farms (n = 10). The density separation method to extract and light microscopic technique to analyze the MPs were employed. A total of 191 MPs particles were recorded, whereas 134 in rearing water ranging from 8-53 µm, 45 in fish feed ranging from 10-88 µm, and 12 in fish flesh ranging from 7-15 µm. Fiber type MPs were the most frequent, contributing 77% in water, 62% in fish feed, and 5% in fish flesh, following fragments and films. Identified MPs were obtained with various colors such as black, blue, brown, translucent, and mixed. MPs were found with the highest abundance in the fish feed (6 particles gm-1), subsequent in water and fish flesh. Identifying the sizes, shapes, colors, and types of MPs is crucial as it affects the interaction and uptake in fish. This study provides an important baseline for future research on the transfer of MPs via the food chain.