The As Seen on TV My Fun Fish Tank uses gravity cleaning technology to clean itself. It makes a perfect, low-maintenance introduction to pet care for children. When you pour clean water on top of the aquarium, dirty water on the bottom pushes out through the cleaning spout. The My Fun Fish cleaning tank utilizes a half-gallon, freshwater aquarium and turns any room into an underwater world of discovery. During the cleaning process, the tank is replenished with fresh, oxygenated water without disturbing the fish.