Disease is one of the leading welfare and production challenges in aquaculture. Managing fish disease effectively and humanely requires integrating welfare principles into health management.
Aquaculture disease management involves welfare trade-offs at every level. Disease itself causes suffering: sea lice feeding on salmon skin damage tissues and osmoregulatory function; bacterial septicemias cause acute illness; parasitic infections of gills cause respiratory distress. Treatment also causes welfare harm: chemical bath treatments (for sea lice) require crowding fish for transfer, exposure to chemically altered water, and handling stress; mechanical delousing systems cause physical injury; emergency culling under outbreak conditions often uses methods (CO2, asphyxiation) with poor welfare profiles. Prevention — through vaccination, biosecurity, site fallowing, and genetic selection for disease resistance — is the most welfare-aligned approach. Norwegian salmon aquaculture demonstrates that systematic vaccination can nearly eliminate antibiotic use while improving fish health and welfare simultaneously. Moving from reactive disease management to proactive health management is the welfare-optimal direction for the industry.