Quote Originally Posted by katia View Post
i don't think the part about them getting depressed or sick is true. in my experience if you keep 2 mice in the same cage they will either breed like freakin' crazy if they're male + female, or once they hit maturity if they're female + female or male + male, they will fight. usually to the death. so no, i don't think having just 1 mouse would be harmful.
I have two tanks, one is full of about 6 females, the other about 5 males. There's no fighting. They all hang out and sleep together, no fighting. I also put mice in with each other without any problem. I pull everyone out, clean the tank put in food/water, put the new additions first, let them wander around in the tank for a bit, before putting in the old crew. There's mild squabbles, but in about an hour, everyone gets along.