I think someone said that a pair of females tend to get on better with a pair of males... I disagree with this and don't really think that there's a difference, although males do best in pairs whilst females CAN be housed in groups, but don't have to be. Pairs is sufficient. With males, they tend to scrap when they first meet and then get on fine, whereas females tend to just have little tiffs over nothing every now and again. They both get on with each other (As was said before, there are a few rare exceptions to this - those that wish to live alone).