Hi,

I've been breeding mice for a while now and I've done a lot of research. Male mice can only be housed ONE to a tank, otherwise they will fight, sometimes to the death. It's not that they aren't used to one another's scent, male mice are just naturally very territorial. I definitely would not suggest putting them together for any length of time. Males usually won't get lonely... they might get bored if you never take them out of their tank, or they don't have enough things to play with. If your mouse is acting abnormal, it might also be because he's sick.