Male neutered mouse with female.

Question
Recently I added three pet store male mice to my family (I had two brothers previously). All three were housed in the same tiny cage in the pet store and got along seemingly fine.  Two are extremely young and very tame (probably from the same litter) but the third is fully grown and the most violent mouse I have ever seen. When I got him home I housed him with his two pet store friends at first, assuming that those three would get along. However after only a day the smallest of the three had a giant gash taken out of his rump. I had to remove Harvey, the violent one, so I introduced him to my other two fully grown mice.  They got along fine in a neutral setting (the coffee table) so after about an hour I put them in a clean cage.  The next day my biggest mouse, the previously dominant one, was all beat up.  His wounds were not serious, but they were numerous.

I've never had a meeting go this badly and I've never seen a mouse, even an older dominant male, treat other mice so badly.  I tried separating him but he is extremely social and he became so depressed he would not run on the wheel or eat.  I'm afraid I may have to take him back to the pet store, but he's so sweet to humans.

I spoke to my vet today and found out he can be neutered.  I don't mind the cost; I love my pets.  However, the vet also warned that if he were treated wrongly as a baby or housed at the breeder's with a lot of other mice he might just be violent; it may have nothing to do with testosterone.

He must be neutered because he cannot live alone anymore.  My question is, would it be best to neuter him and see if he can get along with other males, or should I find him a female once he's fixed since they obviously won't be able to mate?  Would the partner being female even make a difference?

Thank you for your advice,

Stephani


Answer
Dear Stephani,
thank yu for your question.
It absolutely normal for male mice not to get along and introducing adult male mice almost never works, especially when they have enough room. I agree that neutering him is the best option, he will be a lot friendlier after that. But it doesn't work instantly and he may never be able to live with other male mice. To introduce a neutered male to other males, neutered or un-neutered, you have to wait at least six months because they will keep behaving and smelling more or less like normal males for that long (at least to other mice, the smell humans notice will get less after a months or even sooner until he smells no more than a female).
Females are the best company for him, you just need to wait six weeks because he may still be able to mate successfully once after being neutered. After six weeks, he will be fine with females. I introduced a lot of neutered males to females and it always worked, they are great together. Introducing neutered males is a bit more tricky and may not work at all.
I hope I was of some help to you
Jennifer