How Many Male Or Female Mice Should I Keep Together?

Do you want them to mate? If you put females in with one ore more males, the pheromones from the males present in their urine will bring on estrus in the adult females and will cause the young females to mature more quickly (they'll go into heat and start mating). Of course, once a critical mouse population has been reached which is dependent upon the size of the cage, amount of food and water available, and number of mice, the effect will reverse itself (example--by the females having spontaneous abortions and reabsorbing the fetuses). Of course, in captivity, things are often different. Most likely the inbred mice that you get from the pet store will just carry the babies to full term and then eat them...

You should keep 10 mice together at a time . 5 boys and 5 girls. They need to mate. If you have an uneven number fighting will occur