Rats and mice are similar creatures, both being rodents and both being popular pets. Pet (fancy) rats are of the classification Rattus Norvegicus – the brown rat while pet mice are Mus Musculus.
While they look similar in physical terms (apart from their size), which might make people think that they can live together in a cage, rats and mice are indeed very different and as such shouldn’t ever be kept in the same cage together.
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Can You Keep Rats and Mice Together?
The short answer is no, you can’t – and never should, for any reason.
The biggest reason to not keep rats and mice together is that rats will hunt and kill mice if they get the chance, and may even eat them.
This is not because rats are mean or vicious (on the contrary, they make absolutely amazing pets and are almost always very loving) but rather because it’s instinctive.
Mice in the wild are hunted by rats because they compete for the same resources, meaning they eat the same foods, occupy the same spaces etc. Because of this, mice are instinctively afraid of rats (even more so than larger predators) and even the scent of a rat alone can terrify mice and cause lots of stress.
Rats will instinctively chase and harm mice because of this, so it’s vital to never keep them in the same spaces, not even in separate cages in the same room.
While they are both rodents, there is a large difference in their husbandry so if you’re looking to keep rats or mice make sure to do your research into how to care for them to keep them happy and healthy.
Can I Keep Rats and Mice as Pets at the Same Time?
You can keep rats and mice at the same time, but they should always be in separate cages and not in the same room as each other.
This is because, as we said earlier, rats will instinctively hunt mice, so the smell of a rat to a mouse can cause huge amounts of stress, and the urge to get to the mice can cause stress to the rat as well.
This is also true for free roam, don’t ever try to free roam rats and mice together for this reason as it will almost always end in bloodshed, and don’t ever try to introduce them.
If you handle rats and mice one after the other, hand washing can help to keep each rodent calm (as this lessens the smell of the other), as can making sure rats and mice have their own toys, cage furnishings etc.
The best thing to do would be to only keep one type of rodent at a time, either rats or mice, to minimise the risk of injury to either party or unnecessary stress. Our article can help you weigh up the options when considering rats or mice as pets.
Can Rats Cohabit With Guinea Pigs, Hamsters or Other Pet Rodents?
You shouldn’t house rats (or mice) with any other kinds of rodents.
Size differences, natural predation, differing dietary needs and the need for different housing types (e.g. the type of cage needed for rats vs gerbils) all factor in to why rats (and other rodents) should never be kept with different species. But those rodents that are social should absolutely be kept with members of their own species. The exception to this would be rodents such as hamsters, which are solitary and prefer to live on their own.
Because rats don’t cohabit with other species of rodents (including mice) in the wild, they shouldn’t be kept together as pets either. However, there is one exception to this rule, and that is in regards to African Soft Fur Rats.
Mice and African Soft Fur Rats
Despite the name, the African Soft Fur Rat is actually a multimammate mouse (meaning it has multiple nipples – 18 in fact!) and due to their close kinship with fancy mice, they can sometimes be housed with them.
While rats should not be housed with them, ASF’s can be housed with mice if great care is taken to introduce them in a safe, gradual way, along with plenty of supervision and respect for their individual needs.
ASF’s are social animals (the same as mice and rats) and need to live in a group of 3 or more to thrive. There has been some success in cohabiting ASF’s and fancy mice in groups and if they are of opposite sexes, there is no need to worry about sudden litters as fancy mice and ASF’s cannot breed (although don’t keep same species male and females together of either species if they’re not neutered!).
The ideal ratio for this combination would be one male fancy mouse to two or more female ASF’s or a group of fancy mouse and ASF females.