Developing practical fish welfare indicators for aquaculture is an active research area. Operational welfare indicators allow farms to monitor and improve fish welfare systematically.
Fish welfare indicator development represents some of the most active current work in animal welfare science. Unlike mammals with well-established behavioral welfare indicators, fish welfare assessment requires species-specific validation of which observable parameters reliably reflect internal welfare states. Progress has been substantial in salmon, where operational welfare indicators including wound scoring, cataract prevalence, fin damage, and behavioral indicators have been validated and are increasingly applied in both regulatory and certification contexts. Extending this work to other commercially important species including tilapia, catfish, and sea bass would expand welfare assessment coverage to billions more farmed fish.