I like to tell pet store managers two different little statements:
If Mother Nature keeps them separate, so should you!
If they do live together in nature, you MUST simulate every natural condition, including wind and rain and vast open spaces. Otherwise their natural mouth and gut bacteria will sicken each other. This is called abuse by negligence and has caused pet stores to have their animals confiscated if animal control officers are on their game and local laws are sensibly written.
The Zombie Mama is here!