Rainbow trout face specific welfare challenges including proliferative kidney disease, bacterial kidney disease, and crowding-induced anaemia that require proactive management for good welfare outcomes in commercial production.
Farmed rainbow trout welfare includes specific disease challenges that cause chronic physiological distress in affected populations. Proliferative kidney disease causes a cluster of welfare impacts including anaemia, reduced immune function, and enlarged spleens that impair normal physiology. The welfare of fish with PKD is compromised over weeks to months of chronic disease progression before mortality. Temperature management is the primary preventive tool, as cooler water reduces parasite reproduction rates and disease expression severity. Crowding adds to disease risk by causing the hypoxia and stress that further suppress immune function in already-vulnerable fish. The integration of disease management with stocking density and water temperature control represents the most welfare-effective approach to trout production management.