A mouse and a degu are both social, busy rodents best enjoyed in groups, but the degu is essentially the mouse's concept scaled up in size, lifespan, noise, and engineering. A mouse gives you a tiny, self-contained world in a tank for a year or two. A degu gives you a loud, athletic colony in a tall metal cage for five years or more, with a diet rule — no sugar, ever — that shapes every feeding decision. Choosing between them is choosing between a miniature and a full production.
The mouse: the miniature colony
A mouse colony runs on a small stage. A group of female fancy mice — males are kept alone because they fight — will tunnel through deep bedding, build dome nests, climb every rope and branch offered, and reorganize the whole tank between one evening and the next. Mice are most active around dawn and dusk and through the night, communicate in calls mostly too high to hear, and tame to the point of taking seeds from fingers, though their size and speed keep real handling brief and close to a surface. Housing a mouse group is inexpensive and compact, but it must be escape-proof, with narrow bar spacing or a ventilated tank, because a mouse's skull is the only part of her that cannot squeeze through a gap. Expect one to two years per mouse, so the colony renews itself in gentle succession.
The degu: the colony at full volume
A degu colony runs at full volume. Degus are Chilean rodents, larger than a mouse by several times, who live in same-sex pairs or groups and fill their waking hours — conveniently the daytime — with chattering, warbling, wrestling, tail-wagging, and synchronized laps on a big solid wheel. They are enthusiastic, destructive chewers who need a tall metal cage with shelves and branches, because plastic bases and fittings are demolished. Degus also take sand baths, enjoy scattering and foraging, and tame into genuinely interactive pets who will climb an offered arm and investigate pockets. The degu's famous rule is dietary: degus process sugar poorly and are prone to diabetes, so fruit, sweet mixes, and sugary treats are excluded completely in favor of hay, a plain pellet, and greens. Lifespan is five to eight years, a real commitment next to a mouse's.
Housing, diet, and interaction compared
Housing a mouse and housing a degu differ by an order of magnitude. The mouse tank sits on a desk; the degu cage is a piece of furniture, metal throughout, with a wheel big enough for an animal several times a mouse's size and a constant rotation of safe wood to chew. Diet differs in discipline: mice eat a varied seed-and-pellet mix with small treats and forgive experimentation, while the degu's sugar-free rule must be understood by everyone who might feed him, because one child's kind handful of sweet treats is a genuine health risk. Interaction favors the degu — bigger, bolder, awake when you are — but the mouse asks almost nothing of your schedule, while the degu's noise and energy during the day are part of the household soundscape.
Sizing the commitment honestly
Choose the mouse if your space, budget, or time horizon is small and you want the pleasures of watching social rodents without a multi-year promise. Choose the degu if you have room for a tall cage, are home in the daytime to enjoy an animal who is awake with you, and can run a strict no-sugar household policy for his enclosure. Both animals must live with their own kind — a lone degu and a lone female mouse are equally miserable — so either decision is really a decision to keep a group. When a degu group or a mouse colony changes keepers, KinsLe Transferrable Profiles moves their profiles with the colony makeup, ages, and feeding rules recorded, which for a degu means the sugar-free warning arrives in writing, not as an afterthought.