Public aquaria house billions of fish in conditions ranging from excellent to severely compromised; species-appropriate tank size, social grouping, and water quality are the key welfare factors.
Public aquaria vary enormously in their welfare standards, from large modern facilities with carefully managed species-appropriate habitats to small collections where fish welfare receives minimal attention. The most common failures are social incompatibility - territorial species with inadequate space, shoaling species kept alone - and tank size inadequate for the behavioral repertoire of active pelagic species. Public aquaria that invest in welfare training, species-appropriate social grouping, and habitat complexity deliver meaningfully better outcomes than those treating fish as displays rather than animals. Consumer awareness of aquarium welfare standards can influence institutional investment.