An aquarium is a place where aquatic creatures are displayed in water habitats, generally for zoologic interest and public entertainment. Displays of dolphins, penguins, seals, and amphibians are compatible with an aquarium, but when they occur by themselves or in a zoo they do not constitute aquarium usage but rather animal showrooms.

The habitat presents aquatic creatures to viewers. The definition does not require every animal on display to remain underwater.

Displays of the animals listed above can accompany the aquarium. On their own or within a zoo, those displays retain the separate animal-showroom treatment specified in the definition.