Oligosarus are South American so I would not put them with any Central American cichlids, much different water requirments, plus Centrals tend to be aggressive and the Oligosarus is not towards non-cospecifics, they just eat anything small enough to fit into their mouth. I've had a lot of the Uruguay species and I always kept them in with similar sized Gymnogeohagus, they can get agressive towards each other, especially the males, so it's hit or miss on keeping more than one together. Depending on which species you have they can mature between 8-18". Nice fish I always bring a few back on collecting trips. Ken