Public aquariums house millions of fish whose welfare receives far less attention than charismatic mammals. Evidence-based fish husbandry is improving but remains underdeveloped.
Fish in public aquariums are exposed to stress from visitor proximity, artificial lighting schedules, and crowded exhibit conditions. Species-appropriate tank size is frequently insufficient for naturally wide-ranging pelagic fish. Social housing must match wild social structures: solitary species kept in groups and social species kept alone both show welfare problems. Cyanide-caught fish from non-certified suppliers carry internal organ damage causing premature death. Aquarium husbandry is improving as fish sentience recognition grows, but lags behind mammal and bird care in evidence-based practice. Staff training in fish behavior and welfare indicators is essential for improving outcomes.