Hello Evo. We have a firemouth that we recently put in with male africans, because he was not aggressive enough to be in with our bigger Cental Americans (got too picked on), was a little too aggressive with our new bolivian rams, so we didnt want to get rid of him, and we tried him with the africans, and he definitely holds his own. I do not have aceis, so I do not know how they would do with the firemouth. In my opinion, if thats what you want, why not try it, if it does not work out, Im sure you can get rid of some fish. So far, our firemouth has done fine with ours. :fish: