Rainbow trout are one of the most widely farmed cold-water fish globally, with welfare issues specific to their flow-dependent physiology and sensitivity to crowding and handling stress.
Rainbow trout welfare in aquaculture is significantly affected by their temperature sensitivity and flow requirements. Climate change warming of freshwater sources threatens the feasibility of welfare-positive trout farming in some regions, forcing compromised conditions. Grading operations — necessary for uniformity — cause repeated acute stress events across the production cycle. The welfare benefits of lower stocking densities (reduced fin damage, less aggression, better access to oxygenated water) are well-documented but economically disincentivized. Disease events cause mass suffering when prevention through water quality management fails. Compared to salmon, trout welfare has received less research attention despite similar sentience considerations and a comparable production scale.