No need to get rid of your Ectodus, these are interesting and stunning fishes
Xenotilapia spiloptera would be good tankmates for your Ectodus (actually I hoped these were available in your area when I asked
). They will properly stick to the rocky part of your tank, while the Ectodus will occupy the open sand. X. spiloptera is a bi-parental mouthbrooder which doesn't build nests, but will stake out a small territory near some rocks to spawn, so they will not collide with the Ectodus during spawning
You will have two interesting reproduction strategies represented in your tank: maternal mouthbrooding with beautiful displaying and nestbuilding males, and bi-parental mouthbrooding with a fascinating prolonged period of broodcare - that's not bad at all!
All the best, Thomas