水族箱又称为水族缸或水族槽，是为观赏用、专门饲养水生动植物的生态箱，通常至少有一面为透明的玻璃或高强度的塑料。水族箱内人工饲养的通常为鱼类，但亦可是无脊椎动物、两栖动物、海洋哺乳动物或爬行动物和适应水中生长的植物。水族饲养是世界各地盛行的嗜好之一，全球约有6千万名爱好者，并持续成长。

人们很早就懂得饲养水族，但直到1850年代，玻璃所制成的水族箱成为当时的一个新玩意，人类水族从由上到下的变成侧面的立体欣赏场景。随着发展出更复杂的水族系统如照明、过滤系统，水族鱼变得更加健康。

海洋生物馆里的水族箱可以非常巨大，以阿拉斯加水族馆为例，水族箱容量逹5,400立方米，饲养着约580个水生生物品种。

An aquarium (plural: aquariums or aquaria) is a vivarium of any size having at least one transparent side in which water-dwelling plants or animals are kept and displayed. Fishkeepers use aquaria to keep fish, invertebrates, amphibians, aquatic reptiles such as turtles, and aquatic plants. The term, coined by English naturalist Philip Henry Gosse, combines the Latin root aqua, meaning water, with the suffix -arium, meaning "a place for relating to". The aquarium principle was fully developed in 1850 by the chemist Robert Warington, who explained that plants added to water in a container would give off enough oxygen to support animals, so long as their numbers do not grow too large. The aquarium craze was launched in early Victorian England by Gosse, who created and stocked the first public aquarium at the London Zoo in 1853, and published the first manual, The Aquarium: An Unveiling of the Wonders of the Deep Sea in 1854.