Public aquariums house millions of fish in carefully designed exhibits, but the welfare of display fish is rarely assessed with the same rigor applied to charismatic mammals. Modern aquarium welfare science is developing new standards.
Fish welfare in public aquariums has historically received minimal attention because the staff and visitors who care about mammal welfare have rarely extended that care to fish. Yet display fish in inadequate environments show the same indicators of poor welfare as mammals - stereotypic repetitive behavior, reduced activity, poor health outcomes, and shortened lifespan. Large sharks in tanks too small for their ranging behavior show stereotypic circling behavior that is the marine equivalent of zoo carnivore pacing. Reef fish without adequate hiding structures show elevated stress responses in the presence of visitors. The aquarium industry is beginning to develop welfare standards for display fish, but progress is slower than for other captive animals.