- More mice mean more cages/tanks.
- More cages/tanks need more space.
- More mice also smell more.
- More mice mean less of your time for each mouse.
- More mice mean you have to spend more time for the basic care.
- More mice mean bigger expenses.
- More mice mean that you are more likely to run into problems that need vet care.
- Breeding mice means that there will be babies you have to place into good new homes.
- Good homes may be very hard to find.
- You are not going to make money with breeding mice. That is, not if you do it responsibly!