Trout are highly susceptible to infectious diseases in aquaculture settings, and disease management has significant welfare implications. Balancing prevention, treatment, and productivity requires welfare-centered decision-making.
Disease in farmed trout causes welfare problems ranging from the acute distress of mass mortality events to the chronic suffering of fish with progressive infections. A fish with furunculosis developing skin ulcers or one with IPN experiencing intestinal inflammation and hemorrhage is suffering in ways that are not fundamentally different from disease suffering in vertebrates more traditionally considered welfare-relevant. Disease prevention through vaccination, optimal water quality management, and reduced stocking density is both welfare-positive and economically rational. When disease occurs despite prevention, rapid diagnosis and appropriate treatment (including culling of severely affected individuals to prevent prolonged suffering) constitutes a welfare-positive response.