how big is the jd? They usually can get pretty aggressive depending on the individual and from what I have seen its likely it'll get more aggressive as it gets older. Sometimes the aggression will focus on individuals in the tank and other times it will be against all fish. With that stock I wouldnt be surprised if you have some serious aggression issues and I'd only expect them to get worse as they grow. If it was me i'd pull out the bully and re-home it and repeat with the next bully if one arises