bethany

I got 2 sisters from petco 5 days ago and one died (I think from disease. She was also much smaller). But i got another mouse today and she kept attacking mauwi (the first one I got). It got really bad and happened 4 times, each time I yelled and usually it stopped the sisters but the new one just kept going. I was petting Mauwi and she has scratches on her. I returned the new mouse because I do not have another tank for the other. What should I do to keep my mouse healthy and happy???? Mauwi is on the bottom and Dakota was her sister. Mauwi faught a little bit but eventually stopped and wasnt too bad.