Mice will not, for example, be found clinging upside-down to the cage ceiling begging to be let out as soon as they hear you open the door. In fact, tame mice will readily play on you, but will rarely play with you. On the other hand, mice will not take great delight in running riot over your house, peeling wallpaper off the walls, chewing the sofa, throwing things off shelves, stealing food and useless trinkets, or any other of those cute things rats do. This is mainly because mice don't need to be given the run of your house in order to have fun. Generally, mice are much less demanding and less destructive than rats and it is easier to keep them amused.
Mice are also cheaper and easier to house than rats.
While a two foot aquarium would be a slightly cramped home for a pair of rats, it would make a great pad for a couple of mice. Mice have attractions all of their own, but they are also a good choice of pet for those who would like rats, but do not have the time to give them the attention they need, or the space for a large cage. They should be kept in at least pairs, and preferably in larger groups. A single mouse will generally be bored and miserable-no amount of human attention can replace the communication, grooming and constant companionship of another member of its own species. Single mice are not good pets-they tend to hide away for most of the day and are far less active than mice kept in groups, possibly because they are depressed.