Evidence of Microplastics in Gut Content of Grass Carp (Ctenopharyngodon idella) Fingerlings and their Effects on Growth Performance and Body Composition

Abstract Microplastics (MPs) are emerging pollutants that may affect the aquatic life, including fish, raised in aquaculture. The purpose of this study was to determine the effects of biodegradable-MPs mixed in canola meal based diet on the growth performance, body composition, nutrient digestibility and gut content of grass carp fingerlings. For this purpose, six canola meal based diets were prepared including one control diet (without addition of MPs) and five other diets containing 1%, 3%, 5%, 7% and 9% MPs. 270 fingerlings were fed twice for 60 days at a rate of 5% of their wet weight. Effect of each treatment on the weight gain, feed conversion ratio (FCR), nutrient digestibility, gut performance and body composition was calculated by standard procedures. Highest value for growth, nutrient digestibility and no damage to gut was observed in fish fed control diet. Results showed that there was significant decrease (P<0.05) in growth and increase in FCR in fish fed 9% biodegradable-MPs added diet. Nutrient digestibility and body composition of grass carp was highly affected by microplastics. Microplastics also caused severe damage to gut of fish including, tissue damage, vacuolization and necrosis of enterocytes.