Scatphagus-- it means ahem, as you would say--poop eater. They eat other fish's waste. They vaguely resemble discus. All the fish mentioned @ Deadliestviper7 <(think is great) are prospective, proven tank mates for your species. As I recall from my research; they are each reputed to be fairly non aggressive. I think one of them--eclipse catfish can grow to 12 inches. I just got a Yo-yo loaches. Happy busy fish with beautiful markings. Also long tailed long Finned Cherry Barbs. They look somewhat like like a shark but with veil tails. Another beautiful fish. Not as aggressive as tiger Barbs, but more pushy than the peaceful long Finned Albino Cherry Barbs.
The Yo-yo loaches are reputed to be good tankmankates for your fish. My Yo-yo loaches can grow to 6-8 inches. I got a couple that are smaller 3 inches--these appeared robust and healthy. I have them in my passive tank for now. When they grow larger I will put them in with my pushy large golden lab and see how they fare. Likely they will end up in with my Senegals--Swamp Dragons.