Rainbow trout farmed in net pens and raceways face behavioral welfare challenges from their active nature and need for environmental complexity that intensive systems rarely provide.
Rainbow trout behavioral welfare is constrained by the mismatch between the complex, variable river environments they evolved in and the uniform, featureless tanks typical of commercial aquaculture. Wild trout navigate complex currents, hunt prey, establish territories, and interact with varied physical environments throughout their lives. Farmed trout denied this complexity show abnormal behavioral indicators including fin damage from conspecific attacks and the behavioral monotony of constant circular swimming patterns in circular tanks. Environmental enrichment that provides current variation, visual complexity, and reduced competitive feeding pressure substantially improves behavioral welfare indicators. The challenge is implementing enrichment in systems designed primarily for production efficiency rather than behavioral welfare.