Wire cages are not recommended as they can be too drafty, allow the bedding to fall out, are harder to clean and disinfect, and corrode after long exposure to urine. If wire shelves are used in the cage for the animals to climb on, they should be made of ½ by ½ inch wire as a rat’s back foot can get caught in 1 by ½ inch wire and break a leg.
For two rats, a 15 gallon tank (or larger) is a good size. Two female mice (or one male mouse) may be housed in a 5-gallon tank. This will provide adequate room for a house, wheel, feed dish, and water bottle.
If you have several female mice, then try to get the largest tank you can and have fun creating a playground for them. Watching them will give you hours of entertainment!
The cage should be placed either on a table, dresser, or shelf (not above eye level!), away from direct sun or drafts. Extreme temperatures should be avoided.