Fantasy 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 aquatic creatures, which could never be kept as pets such as Blue whales, dolphins, Seals and Killer whales to populate their tanks. 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.