ok i am brand new to breeding mice, and i just got my mice on friday. i keep hearing from people that once your female gets pregnant, you have to move the male or female . but why do you have to move them? and is it nesscessary , and i have another question , how do you tell which mouse is the male, when i got them from petco, i told them i wanted a male and female, they didnt tell me which one was which.