Rainbow trout are one of the most widely farmed fish globally, and evidence increasingly shows that their welfare in aquaculture systems deserves serious attention — from stocking density to slaughter methods.
Rainbow trout welfare in aquaculture deserves serious consideration given the strength of evidence for fish sentience. Trout show avoidance of noxious stimuli, nociceptive responses, stress physiology, and behavioral indicators of pain. In aquaculture, the key welfare challenges are stocking density (high density causes chronic stress and aggression), water quality (low oxygen causes gasping and physiological stress), disease management (sea lice in sea-run systems, bacterial infections in freshwater), and slaughter (many trout are killed by CO2 narcosis or live chilling, which are associated with significant distress). Better-practice farms use lower stocking densities, excellent water quality management, and percussive or electrical stunning before slaughter.