Mouse
3
I had mice as a small child. They made fairly good pet, and we enjoyed them. They do not "play" and are more interested in exploring whomever they are on or getting away. They are smart and can easily escape an improper enclosure. Females can do good in a pair and so can males, but males are a bit more territorial as they age and you can get brawls, but this is uncommon in groups smaller then 4. Not my first pick for a pet.