Public aquariums house hundreds of millions of fish globally. Welfare standards for fish in captivity have developed more slowly than for charismatic vertebrates, creating significant welfare gaps in some institutions.
Fish welfare in public aquariums has historically received less attention than mammal and bird welfare, reflecting assumptions about fish sentience that are increasingly unsupported by science. Fish show learned fear, stress responses, social preferences, and in some species problem-solving that suggests rich inner lives. Welfare-conscious aquarium design requires adequate tank volume and complexity, appropriate social grouping, feeding opportunities that engage foraging motivation, and protection from public disturbance. The most welfare-positive aquariums integrate education about fish sentience with husbandry standards that reflect it. Touch pool exhibits, where fish cannot escape repeated human contact, are particularly welfare-concerning.