Disease is a major welfare challenge in intensive aquaculture. Management approaches that reduce disease occurrence and treat it effectively without over-reliance on antibiotics are central to improving fish welfare.
Disease in aquaculture causes welfare harm through pain, behavioural impairment, reduced feed intake, and mortality. The welfare impact of disease is often chronic and diffuse: subclinically infected fish experience reduced quality of life before showing obvious clinical signs. Prevention through vaccination, good husbandry, and biosecurity is the highest-welfare approach and also reduces economic losses. Antibiotic use, while sometimes necessary, should follow veterinary prescription, be species-appropriate and dose-accurate, and be accompanied by disease investigation to address the root cause. The development of effective vaccines for key aquaculture pathogens represents a major welfare advance; extending this success to more species and disease challenges is a research priority.