I buy two at a time (Kashmire will only eat one a week) and then keep them in a Kritter Keeper with Aspen, some food and a tiny bowl with water that I have to clean daily. Usually only one mouse lives there at a time (the second normally is offered later the same day I buy them to Kashmire- Saturdays). I do it for convenience, but it's definitely a smelly animal, even with just one.