Microplastic pollution is pervasive in aquatic environments, affecting fish welfare through ingestion, physical harm and the toxic chemicals that plastics carry.
Microplastic ingestion affects fish welfare through multiple pathways. Gut blockage and internal damage cause direct physical harm. Ingesting plastics instead of food reduces nutritional intake, causing hunger and malnutrition even in environments with adequate natural food. The chemical burden of persistent organic pollutants absorbed onto plastic surfaces adds toxic stress. Research has also documented behavioral changes in fish exposed to microplastic-contaminated water - altered predator avoidance, reduced social cohesion and disrupted reproductive behavior - suggesting impacts that extend beyond physical health. While the welfare significance of individual microplastic particles is debated, the systemic contamination of aquatic food webs represents a pervasive harm to billions of fish.