WHATS GOING ON? The male mouse is aggressive

[Lord Sorril]

so i am attempting breeding mice for my ball python. i originally only had 2 mice, a male and a female, until i read that more females are necessary.

A 1:1 (Male:Female) is usually fine for mating.

when i just had the male and female i periodically herd them squeaking really loud and i just figured that they were mating. after a few days, i noticed that the female stayed in hiding and i only saw the male come out, and when i did check to see if the female was ok, i noticed that she had what looked like a spot of blood and it worried me.

There are many different genetic lines of mice. Some of them are prone to aggression.

i just figured that if i add a couple more females it would give that particular female a break from the male.

That is sound logic.

i see that the male is attacking the same female but even more aggressively, and i again had to reach my hand in and get him off her. i removed him from the rest of the mice and put him in a plastic rodent container and came here to find out what to do! HELP!

So: First things first: Are you able to confirm that the 'female' that is being attacked by the male is actually a female and not an undefined male? Sometimes people sex white mice wrong because their reproductive parts are not as obvious as ones with darker colors. Two males that were not raised together will definitely draw blood.

I won't get into the details of mouse biology, but, if your male mates with the female(s) enough times he shouldn't continue to harass them. Some people may recommend rotating the male through the females and then eliminating the male when you have a replacement available. My experience is that aggression is usually an inherited trait--if you really do have a 1:3 and the male is still fighting then you will want to pick up a different male.