I've found with American cichlids is that if you grow them up together in a reasonably sized tank, more often than not you can can have fish that normally wouldn't work together actually coexist. Ex I had a 125 with fully grown; jag, green Severum, Dempsey, convict, 2 large Angels, green terror, ornate Bicher. They were all males, raised together, my filtration was 20x an hour (3 canister filters and 2 HOB aqua clear110) and very well fed. I also made sure to change the decorations every week with weekly water change, I found that if it stayed the same way to long then they would start to get territorial and fights would start. I miss that tank.....