Rainbow trout is one of the world's most farmed fish species, with welfare challenges around density, crowding stress, and pre-slaughter handling.
Farmed trout welfare has received more scientific attention than most other farmed fish species, partly because they are farmed in temperate countries with stronger welfare cultures. Evidence from the early 2000s (Sneddon et al.) established that trout show pain responses to noxious stimuli - a landmark finding for fish welfare policy. Crowding stress in intensive trout farming causes chronic welfare harm through immune suppression, injury, and physiological stress. Pre-slaughter stunning with percussive methods provides welfare-positive death when properly applied, and some certification schemes now require this. Trout welfare represents a model case for applying welfare science to aquaculture.