Providing environmental complexity and enrichment for farmed fish can improve welfare by allowing natural behavioral expression and reducing chronic stress.
Fish environmental enrichment is a relatively recent welfare consideration that is gaining traction as evidence for fish sentience and behavioral needs accumulates. Farmed fish in barren tanks exhibit behavioral abnormalities analogous to those seen in land animals in impoverished environments — abnormal repetitive movements, fin damage from chasing, and reduced immune function from chronic stress. Providing environmental complexity through substrate, flow variation, and light management gives fish behavioral choices and opportunities to express species-typical behavior. These interventions often have minimal cost and can improve both welfare and production outcomes through reduced stress.