Rainbow trout are one of the most widely farmed fish globally, with welfare research providing clear guidance on stocking density, environmental needs, and slaughter methods.
Rainbow trout welfare research is among the most developed of any farmed fish species, providing a scientific foundation for welfare standards. Yet implementation of those standards remains inconsistent globally. Overcrowding is the most pervasive welfare problem — fish unable to orient naturally, with fin damage from conspecific biting, are suffering chronically. Water temperature management is critical; trout in water above their thermal optimum show physiological stress. Slaughter method matters enormously: electrical stunning followed by rapid killing prevents the prolonged suffering of asphyxiation in air or live evisceration. CO2 — while effective — is aversive during the period before loss of consciousness. The science is clear; the challenge is adoption.