An aquarium (plural: aquariums or aquaria) is a glass box of any size with one clear side where plants or aquatic animals are kept. A container for aquatic life, either fresh water or sea, where a collection of aquatic life is shown.

Freshwater fish are those that spend part or all of their life in freshwater, such as lakes & rivers, with less than 1.05% salt.

Marine fish, also called Saltwater fish, lives in seawater. These kind of fishes can swim and live alone or in a large group called a school.