Fish welfare deserves priority attention because the number of fish affected by human activities vastly exceeds all other animal use combined; addressing fish welfare would improve more animal lives per effort than almost any other intervention.
The numbers case for prioritising fish welfare is compelling. The annual mortality of fish from human causes — fishing and aquaculture combined — exceeds all other vertebrate animal use by orders of magnitude. If fish have welfare that matters morally even at a fraction of the level of mammals, the aggregate suffering involved in global fishing practices represents one of the largest single sources of preventable animal suffering in the world. Yet fish welfare receives a fraction of the scientific, regulatory, and advocacy attention directed at farm animals. This imbalance between welfare significance and attention represents one of the most important priorities for animal welfare improvement.