For those having trouble breeding mice. When I was looking for my first colony, I came to find that a lot of pet stores ended up having either all males or retired breeder females. Young females were harder to find. So even if you have the correct sex ratio, you may not have females that can still produce. So stick with it until you find some good breeders and then hold back for future breeders. I've been doing that with great success.

To the OP: I love how your mice are in all different colors. We only have white ones here in NJ.