I love keeping pet mice and sharing care information with other rodent parents online.
Mice fight for the same reasons humans do. Power. Mates. Territory. Sometimes they're bored and need entertainment. Females will fight for their children's safety. And sometimes, they just need to take a swing at the jerk who stepped on their tail. Whatever their reasons, if you keep more than one mouse in a cage, understand that they may fight. If they're males, you can expect it.
What Is a Normal Level of Fighting for Mice?
Like humans, mice will display different levels of aggression, which can range from playful wrestling to fighting to the death. Since mice often live healthier lives in social settings, separating them can lead to loneliness and depression. On the other hand, if you can't identify when their fighting becomes serious, keeping them together might be dangerous or life-threatening for them.
Fighting Between Female Mice
Female mice tend to be less aggressive. I've only seen them fight to prevent another female from getting close to her babies. This situation resolves itself after time. Both mice played well together in settings other than the mother's cage. Chances are if this happens, once the babies are old enough to fend for themselves, mom won't feel the need to fight for them.
Aggression in Male Mice
If you house two or more males together, the situation isn't as simple. Boy mice have an instinct to establish a pecking order. Not being as democratic as humans, they will probably fight each other until one mouse—the alpha—subjugates all the others. This is normal, and you may have to let it go.
Sometimes my mice would squeal in terror in the middle of the night. I separated them, but it didn't do any good. I tried to train the wanna-be alpha that any time he made the others squeak I would put him alone in the travel cage for five to ten minutes. It didn't work. For mice as well as humans, order needs to be established, and you may need to just sit on the sidelines and observe until it's over.
Please note that these animals practice male-on-male mounting as a way of dominating each other. If you see this, it doesn't mean your mouse is gay. While the subordinate mouse may not like it, it doesn't harm him, and breaking up the event probably will make the dominance process last longer.
Once the mice have sorted out which one is king, they probably will continue to fight now and then. Sometimes they're only playing, and other times it serves as a challenge or reminder as to who's in charge. But again, this won't hurt them.
Separating Overly Aggressive Mice
Alpha vs. Bully Mice
When an aggressive mouse fights beyond what is necessary to establish a pecking order, we call it a "bully mouse." Watch the subordinate mice in the cage. They may call uncle by crouching submissively, holding their front paws together in front of them, or even lying on their backs, spreading their legs to the aggressor. If this doesn't stop the fighting, you may have a bully.
If you catch it early, you can break up a serious fight before it starts. Mice will face-off by rearing up on their hind legs. They'll slap their tails against the floor to threaten each other. If you see this, grab them before they bring their teeth into the situation. You won't find an easier time to stop the fight.
How to Break Up a Serious Fight
Never take the submissive mouse out of the cage. When you see bullying, you don't want the bully to think he won, so you have to pull him out for a while—ten or fifteen minutes will usually cool him off. I recommend having at least one cage—even a small one—for each mouse that you own. This way, you never have to scramble for a makeshift holding pen if your mice start squabbling in the middle of the night.
You should be concerned if one of your mice starts bleeding. If someone bites them hard enough that it opens a wound, immediately take the bully out of the cage—use gloves. If they can wound other mice, they can wound you. Keep a pair of leather work gloves by the cage if you have two or more male mice.
Sometimes it can be hard to determine the aggressor. Don't assume. I took my alpha out one night because he constantly picked on one of the smaller mice in his cage. When I held him for a few minutes I noticed his back and bits of his tail were oozing blood. The younger, submissive mouse just got tired of being picked on and he fought back. When this happens, don't ever put them in the same cage again. It may be possible that the fight was a single event, but three days later, the submissive tried to finish the job and gave the alpha a severe beating. If that level of aggression is happening, it's not worth risking the health of your pets.
Always keep an extra cage on hand, and be prepared to separate them permanently at any moment. You may have read about techniques for introducing strange male mice to each other—I wouldn't recommend it. These mice aren't strangers to each other. I wanted to put my mice close together to stave off loneliness in the former submissive, but it just made him mad. Any time the former alpha came close, he would swipe at him and bite through the bars, hoping to resolve their fight.
It was an unfortunate situation, but they've lived quite happily in separate cages, so sometimes you should just let an antisocial mouse be antisocial.
This article is accurate and true to the best of the author’s knowledge. It is not meant to substitute for diagnosis, prognosis, treatment, prescription, or formal and individualized advice from a veterinary medical professional. Animals exhibiting signs and symptoms of distress should be seen by a veterinarian immediately.
Miles on July 31, 2020:
NEVER house male mice together! They WILL fight!
Clarissa on July 14, 2020:
HI . So I recently got 2 male mice and they where form the same litter,( Millo & Coffee ) I really need help . So Millo seems to be really aggressive towards Coffee and at first I thought maybe its just to be Alpha ,but its been 3 weeks and Millo is still being aggressive and it has gotten to the point where he bites Coffee so hard that it bleeds and I can even see how scared he is of Millo ( when I pick Coffee up just to see if he is okay and to give him a break, he doesn'teven want to get off my hand ). Coffee will be running on the wheel and Millo will just attack him and even though he squeals the fighting does not stop, but when I put something to separate them Millo wants to digg under it to get to Coffee . I am really scared and need help Coffees tail and but is full off bite marks and blood. Please
bjfjbfhguerfygryf on June 18, 2020:
i read to find out why my friends mouse killed the other and they are both girls
Mandy Bonarrigo on February 20, 2020:
Okay, thanks for the response and advice! I will have to get a new cage ASAP then.
Mystic Baby Jade on February 20, 2020:
Mandy, it might be able to work if you keep the dad mouse with his sons and don't ever separate them.
I separated my young baby males from their sisters soon after they were able to start running around & were eating on their own. However, the dad might impregnate the mother mouse again by then, so you might have to move the father before then.
I had one male who always lived alone & he was fine with it, as long as I gave him extra attention and lots of things to occupy him. If he's alone, you will have to provide him with more interaction, since he won't have other mice to interact with.
It can be as simple as rearranging his cage everytime you clean it, providing toilet paper tubes to play with, and giving him scraps of paper to recreate a new nest, every time you clean his cage. He needs the mental simulation of having things to do & figure out. Also, get him out as much as possible, if he's alone.
Mandy Bonarrigo on February 19, 2020:
I have a pair of mice that made babies (I was told I was buying two females. Then one was pregnant so I got the picture. She had a litter of six, all but one died, then the mom died, now the Dad got his daughter pregnant and she has had about 8?). The babies are 10 days old and the whole family is still in the same cage. I want to separate the Dad and the sons into one cage and the Mom and the daughters into another, after all the babies are weaned.
Do you think this will work with the father and sons living together?
And when can the Mom get pregnant again? I want to separate Larry, the Dad/grandad, before that can happen but don’t want him lonely.
Mystic Baby Jade on February 19, 2020:
Keiko & Apage; scroll down and read some of my replies to others, on this subject & see my suggestions.
Mice are little adorable weirdos, who are VERY territorial.
Apaige on February 18, 2020:
I have three mice.They all grew up together in the same pet store. Two I got together, then a week later I got a third, from the same store. One of my mice was fine with the new comer, however the second one was not and they fought. There was also a lot of squeaking involved before the fight.
I was told they would be fine with each other because they grew up together. Am I missing something?
KeikoKittine24 on February 16, 2020:
I have two female mice "Cookies and Cream", the third female is smokey, She is a bit younger than the other two but we got her from the pet store a week later.
She is about half the size of Cookies and Cream, every time we try and put them together it starts out OK a few sniffs or chases around the cage, but the it turns into a battle both of them team up on Smokey until we have to separate them.Smokey starts squeaking non-stop no blood or anything. I just think shes scared because shes so small compared to them.
I have to take smokey out, she is the only one we are able to pick up with out her running away, or burying her self in the bedding, she will actually come to our hand when shes had enough.
We have had Smokey for 3 days now and don't know what to do. I want them to get along and be in the same cage, but also don't want to have to keep smokey separated all the time. we made her, her own little cage but i'm afraid if we go get her a friend the same thing will happen with then new one.
What should we do
Mystic Baby Jade on August 06, 2019:
Autumnus, mice are very picky when it comes to new cage mates. From my experience, your older two will probably never accept your newer one. They're very territorial.
The best you can do is to go get a buddy for Themis and keep them away from your other two.
I would view it as a serious menace to Themis. Hypnos was NOT playing.
It's very hard to introduce new mice to others who've already gotten their order established.
Autumnus on August 05, 2019:
I have 3 mice, all of them females.
The first two (Hypnos and Psyché) grew up together and I just recently got the third one (Themis), a baby.
Despite of Hypnos and Psyché being in a different cage from Themis, they are close and the two big ones chew on the bars of their cage, which got me worried.
I tried putting Psyché and Themis in a neutral territory and they seemed to be fine but things changed when it was Hypnos and Themis. Hypnos instantly went bite Themis' tail.
Is she playing or is it a serious menace to Themis?
Should I be worried?
What can I do?
Tbsis on June 27, 2019:
I need help, I have two females from the same litter, I got the first one yesterday, and the second one today, they keep having little fights, what do I do?, is it bad?, r they ok together?.
rip09 on April 23, 2019:
A while back i got 2 white mice. One of them died so i got 2 very young mice.
It was going well, my oldest, Persy took well to them. But then one of the younger ones, Nemesis Got injured, I separated her from the other two until she healed. Now she has no use of one of her front leg but she is doing well. But I’ve noticed lately that my other young mouse Cerberus has been force grooming her, chasing her around, and attacking her. She squeaks coming from Nem are heartbreaking. Just today Cerberus had nem cornered to the point of Nem being on her back feet with her back up against the cage. What do i do. They are all females. My oldest mouse is never attacked and never attacks and there is never any blood drawn. Could it be because Nemesis is crippled. or is Cerberus just mean?
Mystic Baby Jade on April 18, 2019:
Jackie, it's normal for them to have little squabbles all their lives.
It's time to separate them if one is a constant bully, or if another is constantly being bullied. If there isn't any stalking or actual injuries, they might be okay. But if any one of them starts having sores, or losing hair (having it pulled out by another mouse), they should be separated.
Once you separate them, they'll have to stay separated.
You've probably already got this, but make sure there are plenty of spaces for them to get away & hide out from eachother.
My males were the worst when I would clean their cage & put in new objects. I found two things to help that:
1. Leave them in the cage when you clean it, if possible. When you have to remove them, put them all in the same container, with bedding from the dirty cage.
2. Leave some dirty bedding & dirty objects in their cage, after you clean it.
The goal is to leave some things that they've already put their scent on, so that they don't have to reestablish territory afterwards. With the dirty bedding, just kind of scramble it in with the clean bedding, so that their scents are spread around & mixed.
I got to the point of cleaning the walls of the cage and trying to leave their scent on the floor of it, by not cleaning that. Or, not cleaning it every time. Because they will reestablish territory every time you clean the cage out, especially if it's super clean. My females even did that.
Good luck! They're odd little beings!
Jackie Kamins on April 18, 2019:
I adopted 4 male mice, all from the same litter. I brought them home at about 2 months old and it seems that now that they’re growing into maturity they’re fighting more. It’s hard to identify which one or two are picking on the others, but I have a good idea of who it/they could be based on their personalities (they all look the same except for 1 has a white tipped tail). They have 2 connected cages but still wake me up squeaking and fighting at night. I’m wondering if I should just put them in another room and let them battle it out for dominance or if I should separate them. To my knowledge no one has been hurt yet but the way some of the fights sound I’m worried they may escalate as they get stronger and older. Most of the time they get along great, sometimes all four will sleep together in one of their little cotton bedding areas. It’s just the occasional fights that worry me.
Abbey on March 03, 2019:
My mice they fight till one is bleeding but then they sleep together and they do nice with eachother but the one that hurts the other is nicer than the on that gets hurt. They have a 3 story cage and they are both males
Mystic Baby Jade on December 05, 2018:
Zoes Mice: I've had females who did this, too. Sometimes it'll resolve itself in a week or two, and sometimes it never gets resolved. Give Jingle bells some good hiding spots, with escape routes.
If Feather keeps behaving that way, I'd suggest removing Jingle Bells & putting her into another cage, with another mouse (put them into the new cage at the same time).
Zoes Mice on December 05, 2018:
I really hope you get back to me on this. So my mouse, Feather, has recently lost her two sisters over the course of a few months. For companians, I got her two smaller mice, Latte and Jingle Bells. I’ve cleaned their tank completely and for some reason Feather keeps attacking Jingle Bells. I’ve put vanilla on their rumps so it smells the same but it doesn’t work. I currently have no hides but two in their tank. I don’t know if it’s territorial, or just plain aggression.
Hannah Howell on August 21, 2018:
I have three male fancy mice. They are litter mates and I've noticed from the start who the dominant one was. I understand pecking order is established but it really bothers me seeing the one in particular getting beat all the time. I'm thinking of returning the most aggressive one and introducing a different more docile one. I noticed when I put the new one in the cage and took the meanest one out , the second in line of the pecking order got a little snippy but I doubt he'll ever be as mean as the aggressive one..I'm no expert, it's just my gut inclining. Thoughts ?
Cinnomin on August 16, 2018:
I have two male pet mice. And one of them is bigger than the other and I don't know why. I have had them for about 5months now and they have been treating each other very well until a couple weeks ago. Ever since then the bully has been biting and attacking my other mouse. Most fights have resulted in blood. Is it okay if I separated them and gave the bully the smaller cage??? To let the other mouse heal??? I always try and stop the fights, but I know for a fact that they aren't playing around. I have currently read some of the commentary and read that these type of fights can lead to death!
Selena on July 19, 2018:
I've found that keeping the alpha in his own cage can reduce fights. The only issue with that is if one of the others decides he wants to be alpha or the alpha passes.
Deanna on April 21, 2018:
Hello I had a litter of mice and gave my friends the mother and one of the babies and I kept a male one when it was ok to depart.. I went to a pet store and got me a female mouse. I held the female then put her back in her cage then I put my hand in the the males for the scent ...he seemed a little excited then I held her and went to put her in his cage without letting her go he still seemed fine but as soon as I let her go he fought her..what can I do to get them to get along ..mind you before I got the female I went and got another make cause I thought he was a female at first he didn't hesitate either to fight except the males fight was way worse ..
Mystic Baby Jade on April 19, 2018:
Matt, you really should separate your males if they are hurting eachother that badly. I don't know how severe the injuries are, but they'll usually heal themselves if you get the mice away from eachother. If it's really bad, you probably should take them to the vet. They might need antibiotics.
Mystic Baby Jade on April 19, 2018:
Mice mom, they're fighting because they're territorial. Even with all that space, they're still territorial. In *my experience*, it isn't as common for males to fight as much, if they are in a bigger enclosure... So I'm not sure what could be triggering them. There could be one in particular who is just more aggressive & wants the entire area to himself.
They say not to house males together because of all the fighting, but, in my experiences, they do much better if you got them at young ages, at the same time, and if they have a lot of space.
Try watching them to see if you can determine which mouse might be causing the most mayhem. He could be put into his own cage.
Be prepared to put them all into their own cages, though. Mice can be strange little beings.
Females are supposed to be less territorial, but I actually had more severe problems from my girls!
Just watch & study them & see if you can figure out what their triggers are. Good luck!
matt on April 18, 2018:
my two male mice are causing serious wounds to each other, and they wont heal. will a vet treat them, or do i have to? If i have to, how?
mice mom on April 09, 2018:
i have three male mice that run around in a room, they don’t have their own cage each (but will soon) i’ve notice that they fight sometimes at night but never hurt each other. i want to know why they fight? they have a whole room to themselves and they fight as if they were inside a cage together. i can’t tell who’s the one that starts to fight because they’re all albino mice and i can’t tell them apart
Audrey on April 03, 2018:
The other day I got three female mice at my local pet store. One of them is extremely small and is active but gets tired a lot. The other is acting strange. Today I went by the cage and one and the small one were in their nest together. The other mouse tried 3 time to get into the nest with them and the big one ( the one with the small one ) squeaked at her loudly and bit her. I don’t know if the small one is her baby or if she’s “ The Alpha”. What can I do?
Justinian on January 29, 2018:
so I got three mice a little while back. i have them in a 10 gallon tank and i got one more a week or so later and one is a bully and hurting the smallest one pulling its hair out
S.c on November 10, 2017:
Hi, I recently got two female mice who are born from the same litter. They seem fine together but at night one of them chases the other and I hear loud squeaks. I think there having small fights. Im not sure if the fights are just playing or serious but neither of them seem to be hurt. They cuddle up to sleep and they are fine together most of the time but I'm not sure if the fights are ok. Please help!
Owen on October 24, 2017:
I just got two young female mice, the fist night they were perfectly fine together but now on the second day the two are having small fights. I haven't seen any real harm but they have had at least one of these small fights per hour. The same mouse always starts it. Usually after the 3-5 second fight is over they will go right back to being fine with each other, even cuddling after the "fight" is this anything serious?
Hann on October 15, 2017:
I have a male and a female together (breeding) this is my first time but I have so much experience with animals I thought it would be ok. The male keeps sniffing her and she's squeaking and it goes into a little fight. I haven't seen any blood and shes younger than him (not by much) but very tiny. They didn't do a lot of what it says in here but should I separate them?
Garlic Freeman on September 23, 2017:
My two male mice are fighting and one is bleeding. I tried putting the aggressor out of the cage for a while but when I put them back in, they continued. Should I separate them permanently or leave them to sort it out? Also, is there anything I need to do about the bleeding?
Russetfur1128 on September 16, 2017:
I've had a male mouse for two weeks and just got another one. The original mouse keeps nipping the new one, but the new one doesn't fight back. Should they be separated, or will they work it out?
GalaxyRat on June 22, 2017:
They are probably OK. As long as they seem to get along. However, if the bigger one gets more aggressive, separate or reintroduce them.
Adam on June 22, 2017:
I have 2 male mice and have so for a few months, one of them is slightly bigger possibly showing he is a little older by a a few weeks or so. He seems to be the more dominant one as he normally chases and picks on the smaller one. The smaller one doesn't seem scared and they both sleep in the same house, groom each other and both have access to food and water. They both live in a large tank together. Is the fighting normal or is the smaller one in danger? I'm not sure if I'm just being a paranoid owner or should take a decision which may save hassle later. The fighting happens most days and can happen multiple times in the same day. Could it be possible that the bigger one is bullying the smaller one as he tends to follow him and Harras him even when the little one stands up and pushes him away.
GalaxyRat on June 11, 2017:
As I said before, keep them separated. Also, does the bites draw blood? Do the mice seem to be in pain?
Jade on June 11, 2017:
Hello! I have 2 female mice I just got a new one the other has been living in the cage for a couple weeks no problem with another mouse but she passed away a couple weeks ago so today I got a new female mouse she chases the other mouse around biting her while she squeaks are they fighting or playing?? Because she jumps to get away and squeaks and then they are fine for a couple of mins and then the new one goes and bites her again and I'm concerned
GalaxyRat on May 31, 2017:
I have 2 rats, and I couldn't find a Hub telling me which of my fur babies is dominant. This helped. I was surprised by the mounting... LOL.
And Hi Maddie,
Separate them. You need to introduce again, and that's OK. Put a separator in the cage, and let one mouse have in each half and the other the other half. Get two food bowls and water bowls. I wish you luck.
Madison on May 20, 2017:
Hi! I'm new to the mouse community and I think one of them is bullying the other. I have two girl mice, Matilda, a little albino mouse, and Madonna, a golden hair mouse. I got Matilda first and had her maybe two weeks before I got Madonna to join her. My boyfriend introduced them in what I call their playpen and then in their first cage. Then, we upgraded their cage to a bigger one. The past two months have been fine. But, recently, Madonna has been losing fur and she has a patch of fur gone now that is the size of a quarter. I've been looking up what could cause it. We thought it was the bedding (baking soda is apparently toxic to the little guys so check your bedding!) and got new bedding. That seemed to work, but Madonna was still losing fur. So, I have been searching for solutions all day, checking their diet (peanuts, sunflower seeds, and wheat = possible allergies), if Madonna was "barbering", or if it was mites. Then, I'm sitting on my laptop and I hear Madonna squeak. I know it's Madonna because Matilda is deaf and doesn't make noise. I go over to the cage and their both by the food bowl. I pull Madonna out of the cage and put her in a tote box. I looked at Matilda and noticed that she was at least twice as large as Madonna. Now, Madonna was little when we got her, is a different kind of mice versus Matilda. But, still, there's a huge size difference. I think that Matilda has been keeping food from Madonna and plucking her fur out. I don't have proof besides the incident tonight and my boyfriend thinks I'm paranoid. Should I keep them separated? They were buddies before. Should I reintroduce them tomorrow? Next week, when Madonna's fur possibly comes back? I noticed that this may have started when I brought in two houses. In the first cage, we had a little strawberry that they would sleep in. In this next cage, it came with a little house and we left it in there by itself for a little while. Then, we put the strawberry back in there. I noticed that they don't sleep together as much anymore. Maybe there a territory thing over houses? I'm sorry for the long winded post. I just want to be a good mouse mom.
Shan on May 08, 2017:
Help me asap
Go to your local £land/ £ stretcher and get 2 big plastic tubs with lids. Drill holes all around the sides and cut out a square in the lid and put mesh over it - secure it with zip ties and holes with the drill. Do the same on one of the sides for more ventilation - this is recommended. These are ok cages. this should cost you less than £15/ £20 for 2. Make sure they each have a wheel or flying saucer and you can diy a bottle holder for bin cages with a cardboard tube - look it up. There are many tutorials of how to make these cages and d.i.y pet things on youtube. I hope it helps.
HELP ME ASAP PLEASE on April 10, 2017:
I have 3 male mice and they've been violently fighting with bloody endibgs for weeks. I dot want to give them away, or taje them back to the seller, but im at my wits end. What can i do? I cant afford seperate cages, and im sick of waking up/loosing sleep to them. Help!
Wolflover5x on April 09, 2017:
I have recently become the owner of three female mice. I have owned mice in the past as well but separately. One morning, last week, I woke up to my three females squealing at each other and basically humping one another, so I separated them. I now wonder if that was the wrong thing to do and if I should just put them back together. Please give me advice on what I should do next.
Maggie on April 02, 2017:
"does the suspected bully try to steal food, keep others from eating or socializing, or try to push them out of a certain territory in the cage?"
My white mouse has been eating but the brown and white one chases her around and it seems like they are trying to keep her in the house all of the time. How do I fix this? Can I get a 3rd mouse? They are both female.
Maggie on April 02, 2017:
"does the suspected bully try to steal food, keep others from eating or socializing, or try to push them out of a certain territory in the cage?"
My white mouse has been eating but the brown and white one chases her around and it seems like they are trying to keep her in the house all of the time. How do I fix this? Can I get a 3rd mouse? They are both female.
Xx_EcHoBaT10_xX on March 11, 2017:
I recently got three new female mice all living in a large tank with two levels, their around 8-9 weeks old. Two of them (similar size) started chasing each other around at night, and I'm not sure if its playing or fighting. There's been no injuries or blood. They all curl up, and sleep together fine during the day. It's just when its night, and they chase the other around they also to squeak. However, its just the same mice that keep doing it. I also held the two females who were fighting on one hand, and they were fine being together its really just at night they chase each other, and squeak.
clo on March 05, 2017:
I have 13 mice due to our female mouse giving birth. We had to seperate the males and females today, but there was a slight issue. The mice were in a tank before instead of a cage, but we moved all of the females to the newly bought cage we have. The cage is barred and did have a male mouse in there before them. We did not clean the cage before putting them in, but we do plan to tomorrow. Something strange I noticed though is that the female mother mouse looks anxious and stressed, she is running back and forth and biting the bars. The baby muce in there with her are 23 days old... will she eatthem or will it be okay? Thank you.
abbie on February 09, 2017:
i have four male mice but i am not sure if one of them is a bully or just trying to establish his dominance, he continues nipping the other three, any suggestions? i have already separated him from the others, nevertheless i am afraid he will get lonely. to make the situation worse, one of them is sick, one is small, and the other less dominant was bitten to the point of blood somewhere around his foot by a previous mouse which i returned. i have a teacher who would take him in, but he would be alone. that teacher would inherit the other three so i am not sure what to do. my condition is urgent so please help!
Syd on February 06, 2017:
I have two male mice, Merlin and Arthur. They were from the same litter and I've had them for about a month. A couple nights a week, I'll hear them fighting. It's mostly Arthur jumping on Merlin, biting at his back, and chasing him. Merlin squeaks and runs to hide. Once he's hiding, Arthur is fine and they are good. Is this normal? I haven't seen any blood, but I'm worried that Arthur will hurt Merlin. Merlin is typically gentler and seems to enjoy being handled more than Arthur as well.
Tonianne129 on December 28, 2016:
Does the same apply to rats? I bought two female rats from the pet shop, both 10 weeks old and from the same litter. They've been perfectly fine since leaving the pet shop yesterday, had them out a few times. Got them out not long back, the smaller one was buried in my dressing gown, the bigger was off exploring but came over and went to where the smaller one was, I heard a little short squeek so took the bigger one away, she went back and the same thing happened again. None of them was at all aggressive towards me though when I was taking them away from each other and there's no marks or anything like that and they didn't try to stay fighting when I tried deprecating them. They're both happily together now and I haven't heard a peep.
Mia on December 28, 2016:
I had three female mice living together, when one morning I came in and found one mouse dead from an apparent fight, because I didn't know which mouse it was I left the remaining two together but moved them into a larger cage ... Today I found another mouse dead with its head missing and covered in blood ☹️ I don't want to put anymore mice at risk but I also don't want my mouse to be unhappy. What should I do? Get her a friend or not.
Sarah on August 08, 2016:
I'm having problems with my 5 does. I got a new none recently and everything was fine until a couple of nights ago. She's started attacking all of then other mice. She has andomjbate personality and I'm notnsurenif she's already taken charge, but the squeaks aren't playful. She chased my oldest around the cage at full speed while she was practically screaming and she wouldn't stop. I couldn't tell if she was trying to attack her genitals. At first inthouht she was onkynpicking on Cake but then once cake escapednshe went after one of then others. I saw aiya humping the new mouse the other day son it all very confusing, indont want to separate her because she's be lonely but I don't mnownwhat to do if it gets worse?
Shabree on June 26, 2016:
My fancy mouse Luna (female) just lost her cage mate (also female) so I went to the pet store to adopt two new females to house with Luna since she had been acting depressed. Luna is the biggest. Toffee is in the middle size-wize and Angel is the smallest. I cleaned out the cage and bought new toys as well. I introduced them and then put them all I to the cage (I have a 3-story critter cage with lots of room).
Luna immediately went after the smallest and she managed to nip Toffee on the leg. It's not bleeding but she definitely nicked her. Now Toffee is terrified and won't go to the bottom of the cage unless I remove Luna which I did have to remove her a couple of times for being a bully.
Luna doesn't like to share the house or the wheel I put in there. While they are getting a little braver with Luna she is still chasing them a lot. I'm worried she is going to hurt the littlest one. Sometimes she just sits in a corner and the others can go to the bottom but then at times she will go after them and I'm not sure why.
I'm afraid to leave the 3 of them in there. I know females aren't usually as aggressive but she is acting territorial. None of them have babies and they are definitely not males. How long should I wait before I decide if I need them to live separately because I don't want Luna to be alone, she is actually very sweet, but I'm worried she won't bond with the new mice after losing her last cage mate.
Kastalimire on May 21, 2016:
So I basically rescued a female mouse 9 days ago. Yesterday I got her a companion. The companion is younger and I'm seeing dominance behaviour. It is semi-confusing. They have groomed and slept together. The beginning was good before the 'attacking' started. They have bouts where they are ok and then the older one seems to attack the other causing her to squeak. She seems ok and still running and curious. The older one runs her to her loft and tries to keep her there for the most part. I've checked a few sites and I simply can't tell for sure. I'm assuming a slower integration is needed and may help as the new one ages and grows?
Alyce on February 26, 2016:
Is it possible for a mouse to become a bully because they were bullied? I had one female mouse named Holly whose friend died so I bought two more named Chloe and Crocus. At first Holly chased Chloe around and so whenever she got close Chloe would freeze and squeak and look terrified. It was like she was cringing away from Holly. I tried putting them in a different habitat so Holly wouldn't be jealous of her territory but by then Chloe was already terrified of her. Eventually though, they all seemed to be friends. Later, after Holly died, Chloe began chasing Crocus around (Crocus was a lot smaller) and I would often hear squeaking and the sound of them running around at night and I'm not sure if Chloe was letting Crocus eat. One day Crocus turned up dead but she hadn't shown any signs of being ill so I'm wondering if Chloe might have killed her somehow, although there wasn't any blood. Chloe then lived a long and happy solitary life. I don't know why she would bully Crocus though, they were in the same cage at the pet store and I'm pretty sure they grew up together.
Kelsey on January 29, 2016:
I got two female mice from a pet store yesterday. Both girls were in the same tank with three other girls. When I asked, the employee said she thought they were all from the same litter, but didn't know how old they were- no more than a few months, she said. One of the two mice, Phoebe, the gray one, is very sweet and friendly- likes to be held, snuggly, calm- but she is smaller than all the other mice. She's more like the size of a feeder. The other one, Penny, who is cream, beige, and white, is larger, more energetic, and kind of skittish. She's also pretty fat. I think she might be pregnant since she's fat and her nipples are more visible than Phoebe's.
Whenever Phoebe and Penny go nose to nose, Penny squeaks her displeasure. When they both try to be in their little house, she seems hesitant and squeaks a bunch. I've also seen her push Phoebe's face away when they're both in there. It seems like Phoebe wants to be friends, but Penny hates that idea. I've also noticed a few small cuts on Phoebe's tail. They're not deep or bleeding, but they look like they could be bites. The skin is broken. There's a scratch on her ear, too. I would say it's just Penny being a bully, but Penny is the one that squeaks, not Phoebe. Could Penny be acting like this because she's pregnant and wanting to protect her babies? Phoebe has been very nice to her but isn't acting fearful at all. Also, there is no chasing, and they're both eating fine. Penny just seems to dislike sharing their little house and being too close to Phoebe. No matter where they go nose to nose, even outside the cage, Penny squeaks.
Could getting another small mouse even the score a little? Should I take Penny back and get a less aggressive mouse instead? Or should I just let them work it out?
mirda on August 09, 2015:
I have two male mice. Both are young, but one is a few weeks older than the other. They are almost exactly the same size. I introduced them on neutral territory, they had what I assume now was their "alpha battle", no one was hurt and for weeks they lived perfectly fine together. The only fought I think once until now. All of a sudden the first one started basically attacking the new mouse. Whether they are playing on their wheel or something or eating, or even minding their own.business he will randomly run at the other and sit on his tail and.bite him. The other squeals every time and just last night he started to fight back a little bit. Neither of them have been injured or wounded and their is no blood. I.can't tell whether they are playing, just having a small spat, or seriously fighting. We have a large I think 40 gallon tall tank with about 1'x3' floor space plus things to climb on and hide in. They have already built their nest. We also have a small 10gallon tank we used for my snake when I had it. If they do need separated, how severely would.I need to clean that tank? What could be causing them to fight like this after they lived so well together?
Please help if you can
jplaj (author) from Duluth, MN on July 26, 2015:
That's absolutely normal. Mice don't have great vision, so they identify each other via scent instead--in fact, one of the suggestions for introducing mice to each other is to put a drop of vanilla on their fur near their tail (near the scent glands). Nothing you're describing seems out of the ordinary, though.
Jeannie on July 25, 2015:
Thank you! An update: I forgot to mention, Berwald tries to groom Tino, but, Tino flinches as if he's being nipped and runs away from him. However, they didn't "fight" again after that. Also, is it normal for Ber to be sniffing Tino on his behind? He does it quite often.
jplaj (author) from Duluth, MN on July 25, 2015:
I highly doubt the two mice belong to different species. What you're describing sounds perfectly normal for two male mice from different litters. Ber wants to tell Tino "I'm the boss," and you should watch the situation closely. While they say mice are social animals, that mostly applies to the females, while male mice don't really need friends. They might resolve their pecking order with the occasional squabble (you'll probably never get them to stop fighting completely), but if Tino looks like he's avoiding certain parts of the cage, or if Ber is keeping him away from the food dish, that could be a bigger problem, even if they're not drawing blood.
If you don't want to separate them just yet, give the bully mouse some "time out." This probably won't make him change his bullying ways, but it could give Tino a chance to get to the food and water--and for you to see how he behaves when he's alone in the cage. Always take the bully out of the cage, never the victim, and if you're trying to get them used to living to each other, I'd limit the time-out period to about a half hour. You may also want to check out my hub on How to Introduce Two Pet Mice to the Same Cage.
Jeannie on July 24, 2015:
Hi, I have two male mice, one is a lot younger than my other one. I got my two male mice from Petco, Berwald is an older black mouse whom was adopted, wasn't able to tell the age, and Tino is a light cinnamon sugar color and he's obviously a baby, maybe about a month or less, I'm not sure. The first night I got them: Fabulous. Nothing, no fights, no problem, Berwald was happily grooming little Tino. Second night: I heard squeaking from Tino, and sure enough. Berwald was all over him, but as I read your posts, I couldn't see quite clearly as to whether Tino was frightened or not from Berwald attacking/"attacking" him. I separated it and went back to my book, I heard more squeaking again and sure enough, Ber was at it again. I grabbed Tino out of the cage and looked to make sure he was okay, and he was. I put him back and now he just seems to be cowering in either the bottom of a plastic bottle I put in there, or he's cowering on top of the hut while Ber watches the cage. I'm scared they're truly fighting, but I haven't seen blood yet. And this is only the second night. Is it possible that they're different species and that's causing them to fight? Or that it's not fighting at all?
jplaj (author) from Duluth, MN on May 10, 2015:
Helmet Head: I'm not sure what to tell you. Your mice are definitely fighting and you're probably right--the bully mouse may end up killing his brother. Sometimes you just have to separate them. I built adjoining cages for mine. The bully tried to reach through to take a few swipes at his brother, but after he realized he couldn't do anything, they both seemed to calm down. They could still see each other if they felt the need to socialize, but they couldn't get at each other to cause damage.
You may have to keep them apart. The good news is when mine were nearing about two years old, they calmed down, and we put them in the same cage for a few weeks before they died of old age.
helmet head on May 10, 2015:
We got mice from our neighbor. Her mouse turned out to be pregnant so she gave us the 2 male offspring. They have grown up together and are not even a year old (born in July). They were totally fine until about a month ago. We noticed that one mouse was jumping on the other, and the other was squeaking, but submitting. We separated them for a short time and it seemed to get better, but then my sister noticed a scratch under the bullied mouse's eye. We took him out to make sure he was okay, and noticed that the tops of his front legs were covered in dried blood. im worried that the bully will kill the other.
Please respond soon. Thanks.
jplaj (author) from Duluth, MN on February 02, 2015:
Even girl mice sometimes feel the need to display dominance. Watch them carefully. Is the bully mouse letting the other get food at all? Do they keep their distance from each other most of the time? Does the smaller mouse squeal when she gets pushed around? If so, you may have a problem. Otherwise, it might just be a behavioral issue that they need to get used to.
A) I've found that with the more intelligent mice, blowing a sharp blast of air at them will start to send a picture (kind of like using a spray water bottle on a cat) without actually hurting them.
B) Keep a close eye on the bigger one. Sometimes pet shops make mistakes in sexing their animals. If it starts to look like she's dragging a grape around behind her, put her--him--in his own cage right away.
Heather on February 02, 2015:
i got 2 mice and one is chasing the other around a lot and trying to push her out of a wheel on the outside of there cage now theres 2 wheels in there now as i want to see if they with just use both and see if that helps. and at time trying to take her food and i have seen her case the other out of there nest. and both are girls.
first time i have herd them do this so its a little scary.
i got them both from petsmart they where in the same tank so i am not sure is this one of=s being mean or not but if she hurts the other she is getting taken out right away as i wont staid the other being hurt
jplaj (author) from Duluth, MN on August 31, 2014:
sockybump - After writing this post, I noticed that if we kept the alpha mouse housed on his own but still near the others, none of the others will assume an alpha mentality and will cohabitate just fine. As soon as our alpha died, though, one of the other males started getting really aggressive with the other.
Mystic Baby Jade - I'm guessing that the older newbie is the most alpha out of the six. Watch her personality as she gets older. I'm guessing she'll take over the group. Also, watch their gender. This sounds more like male behavior and is a little extreme in females.
Mystic Baby Jade on August 31, 2014:
I have a new weird thing going on. The two babies are happy and doing great now... but the other, older newbie I left in the cage with the the elders started attacking the white elder, Cream Puff! At least CP knows how to react and is bigger. Situation seems to be calming down.
I used to have rats. A lot of them. Never had these sorts of problems with the rats.
sockybump on August 31, 2014:
This post has been extremely helpful. Myself and my girlfriend have 6 mice. 2 hairless and 4 with hair. (All bucks)
We had heaps of fights between hairless and haired. So much so that one of the hairless is missing is his tail. We now house the hairless (hicks and assange) in a smaller enclosure and they love life.
Infact they dont even fight.
The other 4 mice. Bear, chief, xavier and rogue all get along. Have done for weeks until I cleaned there home out about 3 days ago. Bear instantly started trying to dominate Chief. I let them go it went for a good day on and off. I got up this morning everyone is best buds again. Cleaned the tank again just cos I had some new things to put in. That none of the 6 mice have had and all is still fine :))
Mystic Baby Jade on August 29, 2014:
Jplaj, Thank you so much for taking the time to read my detailed posts & for your advice. :) I appreciate it!
As of tonight, the eldest of the newbies has also started chasing the babies & now hangs out with the original 3.
It's like the mouse version of "The Bad Girls Club"! Haha
So, yes, I'll definitely separate those 2 babies tonight & get out the biggest aquarium I have (100 gallon aquarium) to relocate all of them all to, after the babies have gotten bigger. Hopefully that will work. If nothing else, at least I'll now be able to bond with the two babies while they're still young, without interference from the others!
jplaj (author) from Duluth, MN on August 29, 2014:
Mystic Baby Jade,
They're definitely exhibiting territorial behavior, and you don't want the babies to grow up like that. I suggest separating them into the two groups of three; they'll be happy enough, with each mouse having two friends. If you want them all to live together, wait a few more weeks until the babies have grown up. Then clean out some area where none of the mice has ever been and where they can hang out for a day or two. Introduce all six mice to that new area at the same time and watch them to make sure they're not fighting.
I've seen that behavior in our male mice (the two pictured at the top of this post, actually). Hannibal, the white one, tried to assert his dominance, but would only ever target baby Sasuke. When Sasuke got a little bigger, he started picking fights and almost killed Hannibal.
Mystic Baby Jade on August 28, 2014:
Okay... I've been watching them non stop since my last post. All 3 elders are clearly targeting the smallest mouse. They grab onto her back end and hold on hard. It's odd because if she's already in the burrow and they go in there, they don't do it. They will groom her. But if she comes out, it's "on". I just took the 3 elders out so the babies could have some time to sniff my hand and get treats. They came out immediately and are having a blast. I really don't want to separate them permanently but I hate for the babies to not even be able to roam the cage freely. It's been 2 weeks of this.
Mystic Baby Jade on August 28, 2014:
Thank You for the response! I've watched them a lot - and its just so odd to me... I still haven't picked up on any real pattern. For clarity, the elders are named Peachy, Silverbelle (SB), and Creampuff (CP).
CP was the baby of that group and Peachy is the oldest. SB used to chase CP around. When they had the mansion, all 3 elders could be sleeping and if a newbie came out, they'd get up and go chase the newbies into the corner. They didn't want them in the mansion, on the wheels, or anywhere else. I have food dishes and water bottles on both ends of the cage, and food spread around the entire cage. The newbies had easy access to food and water but the elders still didn't like it.
Anyway, SB, who is quite large, seems to chase the newbies just for fun. Just because they'll run. At first, Peachy just seemed really annoyed they were there - but that seems to have leveled-off. CP wasn't that bad at first but now, she seems to be the main "bad girl". She actually seems to be ANGRY that they're there.
Another strange thing is when I have my hand in the cage and the elders are climbing allover it, the newbies come up to see too, and CP and Peachy attack them. Are they being possessive of my hand? They're getting better about everything... they will share exercise wheels and don't chase them away from food/water... and will even groom/sleep with the newbies. Until A newbie runs OR tries to get in my hand.
One of the newbies is older than the other two, who are quite young. I'll keep my eye on those two babies, to make sure they're not males. I'm still trying to gain the trust of the newbies but its really hard when they can't even sniff me without being scared away.
The "attacks"don't seem too violent- in comparison to a female mouse I used to have, who was really vicious to other mice. It's just been going on for so long! Cats accept a new member faster than this!
Oh, one last thing, there is a male mouse in the room- about 5 feet away. Could his scent be causing some of their behavior? At the pet store they come from, they are housed in a cage that's beneath a cage full of males, so I thought they'd be used to that scent. Sorry again, for such long posts! I just want to try to figure this out!
Although, they do seem to be slowly getting better, except for the hand thing. Crazy little mousies!
jplaj (author) from Duluth, MN on August 28, 2014:
Mystic Baby Jade -
Thanks for the details. They help, even if it is a long post. Initially, I thought the problem was you let the newbies run around in the cage before introducing the elders. Even that small amount of time helps establish a territory. When you put them in the smaller cage, they all went in at the same time, right?
My first reaction is to say they'll be fine. Female mice can still be territorial, but much less so than males. They'll sometimes nip and chase for fun, and as long as they haven't drawn blood or gouged out fur that's probably what they're doing. Keep an eye on them, though. See if they're chasing the newbies out of a specific part of the cage, or if they're preventing them from eating. These are signs of dominance and are not friendly.
Try to notice if one mouse seems more domineering than the rest. I've never experienced this with females, but if we kept an alpha male alone in a cage, as long as he was nearby, the other males could live in a cage together with no conflict. I'd be more hesitant to separate a lone female, though, since they tend to be more social. If it comes to that, you may be better off with two cages of three mice each.
One last thing to look for, if the babies are young enough, sometimes even pet stores can't tell the gender. If one of your mice turns out to be a boy, that might explain the trouble.
I hope this helps.
Mystic Baby Jade on August 28, 2014:
I have 6 female mice in a large 25 gallon aquarium. Three of them had already lived in there for a few weeks. When I got the 3 newbies, I cleaned the cage thoroughly, washed all the exercise wheels & water bottles, and didn't put anything else in there that the originals had ever touched. I put a big, new popsicle-stick mansion in there. (It had 13 rooms). I introduced all of them by putting them into a cage none of them had ever been in before. (Newbies first). They were together for at least 45 minutes & everything was fine. Eventually, I put the newbies into the newly cleaned & redecorated cage, let them run around for about 30 minutes, then put the original 3 in there. After about 30 minutes, the chaos started. Luckily, the newbies had a corner to hide in. They would come out occasionally, only to be chased back into the corner. (No blood, but a lot of pushing & some nipping). My newbies were in that corner for 2 weeks. One of them was more bold & would come out anyway & the elders chased her a little less. I waited to clean the cage, in hopes that they would get used to each other's smells, but ended up cleaning it out yesterday. I noticed the elders didn't chase the newbies while they were in the smaller, temporary cage. It made me wonder if it was because there wasn't really any territory (house) to fight over. So when I put them back in the big, cleaned cage, I only gave them their 3 wheels, some cardboard tubes, and one small burrow. To my surprise, there was no fighting! One of the elders even started to groom the newbies, in the burrow. When I woke up today, ALL the mice were in the burrow together. However, as the day & night progressed, the chaos started again. Sometimes the elders are nice & sometimes they're not. I hate for my newbies to be terrorized like that... Should I keep waiting it out or go ahead & separate them? No blood or missing fur, but lots of nipping, chasing, and squealing.
Also, I took the elders out to play earlier, and they started chasing the newbies when I put them back. Sorry this is so long, but I wanted to give details for a full view of the situation.
jplaj (author) from Duluth, MN on August 12, 2014:
Female behavior is harder to diagnose than for males. There's a good chance they're just playing--even females will wrestle with each other to keep themselves amused, but even girl mice can be bullies. What do the squeaks sound like? Short little chirps generally mean playing. Longer, repeated squeals usually indicate that one mouse wants the other to stop--that's what you want to look out for. If that's the case, you might want to pull the bully out of the cage. Otherwise, watch their behavior for a few nights (does the suspected bully try to steal food, keep others from eating or socializing, or try to push them out of a certain territory in the cage?), and be on the look out for injuries.
Also, does she pick on one mouse specifically or both of the others equally? With our males, we had a situation where the older alpha mouse constantly picked on one of the others, I believe referred to as a "gamma" personality--think the mouse equivalent of nerds on a playground. When the little mouse got bigger, though, he turned out to also have an alpha personality, and almost killed the one who kept picking on him.
Draya Lindgren from Kankakee on August 12, 2014:
Hi, I have 3 does in one cage and one of them seems to be a bully. She chases the other two around every single night and there are multiple times that I hear squeaking. I hate it and I don't know what to do. They fight but there hasn't been blood. Will it stop eventually if I just leave them alone? Or do I have to separate them? Thanks.
Dilon on May 11, 2014:
Yea but mine will just start buying eachother and then they will scrap for like 5seconds and stop they are female and a male
jplaj (author) from Duluth, MN on March 20, 2014:
The simple answer is to separate them. Make sure you have a second cage. Figure out which mouse is initiating the fights and put that one into the new cage. When they get older, they'll mellow out and you can reintroduce them to each other, but you can't really teach a mouse to stop being aggressive.
Generally, you should also avoid housing male and female mice together unless you intend to breed them--you might be witnessing something other than a fight.
Rebecca on March 20, 2014:
What do I do if my females and males are fighting