Occurrence of Microplastics in Fish and Shrimp Feeds

Plastics with particle sizes of 100 nm to 5 mm are known as microplastics. The contamination of seafood-based feeds by larger microplastics (20 μm to 5 mm) is a growing concern. Here, we analyzed fish and shrimp meals. Microplastics were extracted using density separation methods and characterized using scanning micro Fourier transform infrared spectroscopy (μ-FT-IR). The average microplastic abundance in shrimp meal was 10.7 microplastics·100 g^-1. In fish meal, 1.02% of the microplastics were smaller than 1 mm, while most of the microplastics in shrimp meal were 1-5 mm. Eight colors of microplastics were observed; black, red, and orange microplastics have been rarely reported in previous studies. The microplastics found included films, fibers, and fragments, with film-type microplastics being the most common. The main chemical components of fiber-type microplastics were olefins and polyester, while film- and fragment-type microplastics were mainly paraffin and polyethylene. Additional in-depth studies of microplastics in feeds are necessary to provide data support for feed safety assessments.