Rainbow trout are one of the most widely farmed fish species globally, and their welfare in freshwater production systems is an important but often overlooked issue.
Trout at high stocking densities show increased fin damage, elevated stress hormones, and impaired immune function. Slaughter without prior stunning involves a period of consciousness during killing. The evidence base for trout sentience is strong, and their welfare in aquaculture deserves the same level of attention as mammalian species in comparable production volumes.