Rainbow trout is among the most studied farmed fish species for welfare. Evidence on stocking density, handling, and slaughter informs advancing welfare standards.
Rainbow trout welfare science is among the most developed for any farmed fish species, providing a strong evidence base for welfare standards. The evidence for nociception and stress experience in trout is robust, supporting welfare considerations analogous to those for warm-blooded vertebrates in farm welfare policy. Stocking density management is the highest-impact operational factor, affecting behavior, physiology, fin condition, and mortality rates. Handling protocols during grading, vaccination, and harvest should minimize crowding, air exposure, and physical damage. Pre-slaughter welfare is well-studied — electrical stunning followed by gill cutting produces rapid insensibility while CO2 stunning, still used commercially, causes prolonged distress and should be phased out. Consumer demand for certified trout products is creating market incentives for producers to adopt higher-welfare practices.