Question about Male Mice

So we're in the process of beginning to breed mice, and I was curious to know if there were any requirements for the males to be a great stud for the females? We bought 2 females and a male today, and the male is uh not as "endowed" like most other males we seen. Would the males having larger testicles make any difference whatsoever? The male that we got has very small testicles, but let me tell you what, he's pretty aggressive, and tried to nab me on the finger earlier!

Would the size of their testicles matter? Would their general size matter as well?

How old is the male?

Can't really tell, we got the male at the local pet shop.

He may be young still, as long as he's getting the job done :)

He may be a younger male, scared or cold. They can retract their testicles depending on temperature or if they are scared. I have not personally seen any correlation to testicle size and fertility in rodents (or humans :))

We have had problems with our males before, but we found that if we got a young male we would properly feed him and and let him grow to adult size than let him mate with the adult females and that worked alto better than the younger ones that really never did much and didn't do there job. We have a very nice big stud now that does his job everytime. I don't think it much about the testicles but more about the health and the size of the mouse to make sure that he is able to breed. good luck with you cycles. ;)