I've tried to introduce the new girl,Marble but they attack her and she is missing a few spots of fur. I allways stop the fight as son as I see it and I'm affraid to let them be together. All the older girls are 7 months and up and Marble is almost 4 months. I've had many a rat and I've never had this sort of problem. I take them out 1 on 1 and only Juniper doesn't attack but she's alway been a kiss a** type of girl... Plaese Help! I don't want Marble to have to live alone.