I have kept Uaru, and they are very sensitive to nitrate, so you have to be on top of your water changes. They are beautiful peaceful Cichlids and must not be kept alone. I have never found them easy to get hold of (possibly a good thing for them) but they do make very interesting subjects. I believe that you could keep them in with your other fish, as a Firemouth is mostly all bluff (but does require slightly harder water) and they should be fine with Severum. I have never kept Acara, so I cannot comment about these. Mine max'd out at about 8" and were a pleasure to have. If you get some, please keep us updated, as I would love to see their pics on this forum.