Species · Small Pet

Mouse

Mus musculus domestica

The fancy mouse — kept, bred and shown since Victorian times, and the smallest genuinely rewarding mammal in the hobby.

A group of does in a well-furnished tank is one of the best value-for-space animals in pet keeping: busy, curious, endlessly rearranging their world. The rules are short and firm. Does live together; bucks fight unless they grew up together, and mostly live alone; and everything smells — the buck especially — unless cleaning is regular. Lives are short, which is a mercy for a first bereavement and a real cost for anyone who gets attached, and you will get attached.

At a glance

Lifespan: 1.5–3 years
Adult weight: 25–45 g
Daily attention: 30 min, plus all the watching you like
Alone time tolerated: Does in groups; bucks mostly alone
Minimum housing: Tank or barred cage, tight mesh, lots of furniture
Diet: Mouse mix rationed, plus scraps of fresh
Handling: Gentle, brief, over a surface — they are quick
With children: Watch yes; handling only for careful hands
With other pets: Prey animal — keep separate, especially from cats

Breeds · 4 listed

Fancy mice come in dozens of coats and colours from show lines. The husbandry does not change with the paint.

Agouti
Black
Dove
Banded

Right for you if

A small society to watch appeals as much as a pet to hold.
Space and budget are modest and you want them well spent.
Short lifespans are an accepted term, stated up front.
Regular cleaning is a habit, not an ambition.

Wrong for you if

You want one animal that bonds to your hand — choose a rat instead.
The plan was two bucks from the same shop tank; that peace rarely survives maturity.
Odour sensitivity runs the household.
A cat patrols the room. The stress alone is a welfare problem.

Welfare and sourcing — read this part

Mammary tumours are common in mice and can appear anywhere under the skin, because mouse mammary tissue is widely distributed.¹ A weekly once-over with your fingertips is the screening program; lumps in a mouse move fast.
Mycoplasmal infection causes sudden, severe respiratory disease in mice with long-lasting effects.¹ Chattering, clicking or laboured sides in a new mouse is a vet conversation, and quarantine before introducing newcomers is the cheap insurance.
Male mice fight — often savagely — unless they are littermates raised together from birth, and even that peace can break; females barber each other’s whiskers as a dominance habit.² Buy does for a group, and treat a lone buck as the deliberate choice it is.
Buy from a breeder or rescue where you can see the whole colony: clean tank, bright eyes, smooth coats, nobody hunched in a corner. A mouse’s housing history is most of its health history.

Sources

Diseases and Disorders of Mice. MSD Veterinary Manual 2026. Accessed 2026-09-05. International MSD Veterinary Manual Mammary tumours are common in mice and can develop anywhere under the skin, because mice have widely distributed mammary tissue. Mycoplasmal infection causes sudden, severe respiratory disease with long-lasting effects.
Mice and Rats as Pets. MSD Veterinary Manual 2026. Accessed 2026-09-05. International MSD Veterinary Manual Male mice, except littermates raised together from birth, are likely to fight — often savagely, with severe bite wounds. Barbering (a dominant mouse trimming cagemates’ whiskers and fur) is common in female mice caged together.

Every source here was checked, not recalled. Where this page makes a health statement and no source appears against it, that is not an oversight we have hidden — it means the claim is not yet sourced, and the build reports how many are in that state.

Availability, registration and keeping requirements differ from place to place. Check the rules where you live before you commit to any animal — we describe animals, not law.