I recently established a 1.2 mice colony and both girls are now nursing their first litters.

I am by no means an expert, but I did use a 10 gallon tank with sides darkened ( used to be my BP's tank til I moved him to a large tub ), aspen substrate, ample food ( used Diamond dog food which I feed my show dogs ) and water changed every 3 days. I also kept them in a small room with the temp @ constant 70. The male mice does give off a smell, but I change my substrate every 5 days so the smell isn't so bad.

If you are going to try to establish a new colony - start with 1.2 and make sure you sex the rodents yourself. Pick them up. Stay away from the nippy ones as they are more suited as feeders than breeders. Males do pull their balls up inside if nervous, but once they relax it'll come down. Girls also have nipples. It's fairly easy to sex mice or rats - you just have to get your hands on them. I found my mice from a local breeder via CL. And as always, be patient and let nature take its course.

Breeding mice is rewarding for me as I love the genetics that go behind it. The variations of colors and the rate of reproduction mice provide is indeed fascinating. But most importantly, they are a food source for my precious BPs and as a must, given proper care as well.

Don't be discouraged!