Aquarium by DS contains five tanks of differing sizes to choose from, which can then be customized with different backgrounds, plants and accessories such as rocks and bridges. The player can then choose from more than 30 fish to populate their tanks including Clown Fish, Angelfish, Neon Tetra and Guppy. The player must create the correct environment for their chosen pets; from controlling every aspect of their aquarium from the water temperature, the salinity and keeping the tank clean to feeding the fish and choosing suitable tank mates.