The problem is that you have only 2 cichlids in there. That's the worst combination ever. I've seen so many bad advices here about stocking tanks, specially when the tank is 55 gal. People always say the same thing: "Put a gt and a jd, or jd and con, sal and sev, etc..When dealing with agressive cichlids, two individuals is a recipe for disaster. You should add another 2 or more convicts, and try to avoid pairs.