Public aquarium fish welfare presents unique challenges around tank size, water quality, conspecific aggression and the needs of species with vast natural territories.
Aquarium fish welfare varies enormously by species, exhibit design and management quality. Small, reef-associated species in well-designed habitat exhibits with appropriate social groupings can have reasonable welfare; large pelagic species in circular tanks face fundamental constraints on territory and swimming behaviour that cannot be adequately addressed by exhibit design. The welfare challenge for aquariums is honest assessment of which species can have adequate welfare in captivity and which should not be kept regardless of exhibit investment. Moving toward habitat-matched species selection, smaller exhibit fish with complex habitat, and phase-out of inappropriately large pelagic species would improve the welfare profile of most public aquariums.