Generally, putting one male with two females in a single cage will increase the chances of breeding. To prevent fighting, it's important that there's only one male in each cage. If you're not sure which mice are male, gently lift them up by the tail and look between their legs. Most mice reach sexual maturity (males and females) at 4-7 weeks of age. Younger mice generally produce smaller litters and therefore are not typically mated until they reach 6-8 weeks, of age. Mice that have been housed alone or in same-sex pairs will usually not breed successfully if they are older than 6-8 months.
