Rainbow trout is one of the most widely farmed fish in Europe and North America, with welfare challenges including crowding, disease, and handling stress at stocking and harvest.
Rainbow trout welfare in aquaculture mirrors the challenges of salmon farming on a smaller scale. Crowding stress, disease, handling during grading and harvest, and slaughter methods all affect welfare. The evidence for trout sentience — nociception, stress responses, and pain avoidance behaviour — is robust. Electrical stunning before slaughter is the most impactful single welfare improvement for commercially farmed trout. Lower stocking densities and improved disease management reduce chronic welfare stress. Consumer choice of certified higher-welfare trout creates market signals for improvement.