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Mice/Male mouse siblings suddenly fighting



I brought home two male mice from the pet store on February 1st, about a month ago, and for the most part there has been little squabbling and the two were getting along well. I made a very large bin cage for them, I'd say 2 feet by 3 feet, with lots of tunnels and fun things to climb on. Unfortunately, just a few days ago I started to hear loud squeaking, and I checked on them every time I heard it. Up until this evening there were no injuries, but to my dismay I checked on them late tonight and the cream mouse, Ascot, had the smallest bit of red on his side. Not long after, I looked him over again and there was more blood on his rump. I've realized from watching them fight over the past few days that Ascot's housemate, Seiji, was usually the aggressor, which struck me as odd because it has seemed like Ascot was the dominant mouse. I have noticed no blood or injuries on Seiji. I'd planned on getting them a second wheel and putting in an extra nest because I read that might reduce the need to fight over territory, but with seeing blood tonight I had to take action. So, right now Seiji, the bully, is in an aquarium which I placed inside the regular cage, so that they would be unable to fight but could still sort of be together. I hope that was a decent decision.

I really want these two mice to be able to spend their lives together and not be forced to live alone. I am willing to separate them but only at last resort. How should I proceed from here? Should I try keeping them together while adding an extra wheel, more hiding places, and maybe a second floor? Or now that I put Seiji in his own compartment, do I need to reintroduce them after a cooling-off period? This is causing me unimaginable stress because I want more than anything for them to be happy, and it would break my heart to have to separate them for good.

Thank you in advance, and I hope you can help me help my mice!


ANSWER: Dear Erin,

I have bad news for you. Most male mice have to live alone. *Sometimes* litter mates, or a father-son pair, can get along for life if they have never been separated. Sometimes.

Pet store attendants who mislead mouse adopters by saying that males can live together at best are misinformed because they only ever see young mice; at worst they need to sell  more male mice.

They will be fine living each in their own cage, but you will have to give them each some extra love. On the positive side, since you will be their only buddy, they will each be sweeter with you.

Enjoy your little boys. Separately :)



---------- FOLLOW-UP ----------

Seiji and Ascot
Seiji and Ascot  

Actually, I have some possibly good news. As soon as I woke up this morning, I took both of the boys out of their separate cages and put them in my bathtub because I read that a neutral place is good for introducing mice. After only a bit of noiseless quarreling, it was clear that the hierarchy was determined and whenever Seiji came near, Ascot became obviously submissive. I let them explore the bathtub supervised for fifteen or so more minutes and though they interacted, there was no more fighting at all.

I cleaned out another plastic bin and set it up as a cage to give them a neutral space that was safe for them to be in while I was gone today. I put them in at the same time, and the same process occurred. Some brief, quiet wrestling, then submission, and then after that they were fine. I watched them for awhile and right before I left for school they were making a small nest in the corner and snuggling next to each other.

That was a load off my shoulders and I'm going to be very careful about what I do. I'm thinking of leaving them in the neutral cage for a couple more days to see how they act with each other. If there is any more blood, I will separate them for good. Hopefully that doesn't happen!

In the case that I do separate them, what do you think about making a plastic or plastic & mesh divider to split their normal cage in half? Or do I need two completely separate cages?

Thanks for the fast reply, Natasha :)


P.S. I attached a picture of the day I brought them home. Ascot was very tame from the beginning and was eager to crawl on me the first day. Seiji, on the other hand, was not happy, but warmed up to me with a little time and space :)

Hi Erin,

Remember I said *if they have never been separated* which means keep them as close as possible. So the mesh divider would be a better idea. But put them back together (in a clean cage) as soon as possible.

I'm glad they seem to be getting along better.

Squeaks n giggles,



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I can answer questions about raising mice and caring for them as pets, with knowledge from my 38 years of having fancy mice as pets. I have NO MEDICAL TRAINING and you should take a sick mouse to the vet; but if you simply can't, I will try to help you. I LOVE PHOTOS!!! I ALSO LOVE UPDATES! Let me know how the little tyke is doing later on, for better or worse, especially orphans. It also helps me to help the next person. Please first search first: use 'Natasha Mice Mouse' with whatever else your question includes. Or check out these links: **** YOUR FIRST MOUSE (my video; rough draft): **** TEN VIDEOS ON RAISING ORPHANS: **** SEXING MICE: **** And some GREAT MOUSE INFO SITES:


I have had mice for 40 years (since I was 5!). I raised them when I was a child but now I keep all females, and never fewer than three so that if one dies the others are not devastated, because they have each other.

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