Female mice bully

Question
I bought two feeder mice and about a week later bought 2 fancy mice. They all got along fine for the first few weeks. However lately the newer fancy mice have been attacking my feeder mice. They won't let them go to the food bowl or cross their path in anyway. I hear my poor mice squeaking all night from being chased and bitten. Now one of them has a sore on her back. Their in a big 29 gallon tank with lots of room to hide and play and I don't understand what's wrong or how to keep it from happening. The two new mice are very scared of me and one freezes up when i look at her and the other will close her eyes so to stop the chase all i have to do is look at them. The other two are very sweet/tame mice. Occasionally they'll all sleep in the same area tog but usually it's divided. Please help so i don't have to get rid of the newer ones.

Answer
Dear Rebecca,

What a sad situation.  You need to separate the mice.  When mice chase and squeak it's one thing, but when blood is drawn you have to draw the line.  The little feeder mice are going to be dreadfully miserable if the situation continues.  

You may be able to divide the cage somehow.  Please make sure you have a wheel in each side/cage.  It's nice to keep the cages near each other so the mice can still communicate.  

I'm sorry for your mice's trouble and wish them all happy and healthy lives.

squeaks,

Natasha