breeding mice problem

I have been breeding my own mice lately. Once they are weaned I try to keep several (maybe 6 small males) together in a 10 gallon tank to wait to be fed off. What I am finding is that some of the mice have clearly been being picked on - they have bite wounds on their butts.

Why is this happening - is it something I am doing wrong or is it to be expected. Is my only option to separate them??

If someone could chime in on a possible solution that would be great.

Thank you.

Male mice can be extremely territorial, I've had some chase others around and almost kill them. You just have to identify the aggressor and remove him/them.

That man is correct. I know your pain in a se.se I put two soon to be dinners together and one kept bullying the other seperated them and the one that was being picked/humped to death is now a breeder for me. Caught him doing.g the nasty the other day. I'm proud of him now.

If male mice are housed together when young shouldnt have a problem at all when given proper food and water.

If their near females and can smell them they will fight. I have a tub with about 40 adult males and none fight at all...

I think that's called..magic.

Don't house male mice together. After 6-8 weeks they'll start fighting, unless they're been brought up in a strict colony setting. And even then you can have problem mice.