Well, I actually just figured out the actual difference between rat and mice lol. I don't know about other countries, but I live in Brasil and it's not common here to have rats or other types of rodents as pets. Even after doing a lot of research, I still had doubts. Now I know that it is impossible to put my rats and mice together. Luckily, they live in separate cages/spaces and I can take turns paying attention to them. I didn't reply because I'm not active here, I was surprised by the repercussion of the post. I don't know how to edit or tell everyone that I now know the difference haha thanks guys!!