Large-scale commercial production of aquatic animals has accelerated during the past decade, both in terms of total biomass produced and diversity of organisms cultured. As a result, the husbandry practices applied to these animals -- and the welfare states associated with their use -- are emerging issues in national and international science programs, organizations concerned with the treatment of animals, and amongst consumers. This DAO Special brings together a range of perspectives on aquatic animal welfare, from pragmatic empirical science to ethics, philosophy, and animal rights activism.