55 Gallon Aquarium Petsmart (store only, not online) - $99.99 RattyRat's Review: We would not use a 55 gallon tank to house anything more than four female rats or two male rats, maximum. Using tanks to house your rats has it's benefits and it's definite downsides. Tanks are easy to clean by simply scooping out the dirty litter using a dust pan and then spraying it down with disinfectant. Tanks don't have any wire floors to hurt your rats' feet. Tanks completely prevent your rats from kicking any litter out onto the floor. Tanks clear glass sides let you easily view your rats while they play. And tanks are one level, which is perfect for your elderly rats. On the other hand, tanks are very hard to attach toys and accessories to, and tanks have to be kept super clean due to their poor ventilation. You need to clean a tank twice as often as you would a cage to ensure your rats' health. So it really is a tough decision between a tank or cage. In the end, we prefer a cage.