You have three male bolivian rams? That is quite a few. You don't find them aggressive? Anyway, to answer your question: they can be kept together, although it is generally not recommended as their water parameters are quite different. Also, it might be a good idea to flesh out the schooling fish that you already have into schools for 6-8 because, while they may seem fine in small groups, they will show more of their various behaviors in larger groups. Further, if you are thinking about more males, the answer is probably no. German rams tend to be more aggressive than the bolivians, so that is something to keep in mind as well because, even if they are smaller, they do require more floor space, as far as I can tell.