Rainbow trout are among the most widely farmed fish globally. Disease management in trout aquaculture has significant welfare implications given the scale of production and the challenges of treating fish in water.
Disease in farmed trout causes significant individual welfare suffering - from the neurological distress of whirling disease to the pain of furunculosis lesions. Given the scale of trout production, disease events affecting even a fraction of a population represent welfare harm to millions of individuals. Prevention through optimal water quality and stocking density management is more effective for welfare than treatment. Where treatment is necessary, in-feed delivery is less stressful than individual handling. Welfare certification for farmed trout should include disease monitoring, mortality rate reporting, and evidence of preventive management protocols.