quick question... when you "expert hobbiests" give advice is it coming from the text books, personal experience, or what YOU think is right?
My old friend

actually I was wrong the fish is a hemichromis frempongi, now this is the real mean one.
Actually listed as slightly smaller (15cm) to H. fasciatus (20cm) & only moderately aggressive to aggressive depending on the fish. Same family, same water chem, same diet, out of central Ghana. Still more than a handful given your present situation. As before, aside from the facts, this is JMHO. Good Luck