Rainbow trout are among the most commonly farmed fish globally, produced in flow-through streams and recirculating systems with welfare challenges including crowding stress, aggressive behavior, and slaughter practices.
Trout welfare in aquaculture benefits from species characteristics: their preference for structured environments and strong responses to water quality parameters make welfare monitoring through behavioral and water quality indicators relatively accessible. However, the territorial aggression of trout at high densities creates chronic injury from fin and body biting that is managed through stocking density control rather than behavioral solutions. Slaughter practices vary widely — live chilling in ice slurry is common but causes prolonged loss of consciousness compared to electrical stunning, which can induce near-instantaneous insensibility when correctly applied. Welfare certification programs for trout are available and specify improved stocking densities, environmental enrichment where possible, and mandatory pre-slaughter stunning.