Mice need 8" or larger wheel and/or a medium size saucer. Smaller wheels/saucers can cause spine and tail damage
Mice love to climb!
Bedding should be 2"-6" deep
Recommended substrates are Aspen, Kiln Dried Pine or Hemp. Paper bedding has been scientifically proven to not absorb the ammonia from their urine & is not recommended.
Bigger is not always better for mice! Keep in mind that mice are bottom of the food chain prey animals & that fancy mice come from house mice. Where do house mice live? In walls, drawers, etc... really anyplace small enough for them to feel safe. Per scientific studies, the recommendation is 50-100 square inches per mouse. This means a 40-gallon tank needs a minimum of 7-8 mice.
Mice love clutter! The more places they have to hide, the better! Cardboard items make great cheap/free clutter items
Rodents have constantly growing teeth, make sure to provide wooden chews.
Popular enclosures are tanks, terrariums, DIY bin cages & bar cages! The "fun" cages pet stores sell are not appropriate for any small animal, these include PetSmart's Tiny Tales cages and Critter Trails.
Mice should be fed lab blocks; these contain all the needed nutrients. Seed mixes should be avoided as anything other than a treat; mice tend to only eat the "yummy" parts...which means they don't end up getting all the nutrients they need.
Mice are granivores, they do not need fruits & veggies. Fruits are high in sugar and veggies have a high-water content, which can cause diarrhea. You can give them very tiny amounts of fruits/veggies as treats if you'd like, but they do not actually need them nutritionally.
Male mice must live solo, once male mice are mature they can, and will, seriously maim & kill one another. Bucks make great pets & are little attention hogs!
Female mice must live in groups, or pairs at a bare minimum. Groups of 3 or more are highly recommended.