Luck of the draw I guess with regards to aggression. Your 4 inch 'he' is most likely a 'she' by now. I have a spawning Maroon pair in my 77 with Yellow Tang, Singapore Angelfish (like the one in your Avatar), two Mandarin Dragonets and there are few if any battles. A nudge from Mama Maroon from time to time if one of the other scaled inhabitants get a little too close to the clutch of eggs, but nothing major. The Maroon and a Blue Devil Damsel were the first two fish in my tank close to 4 years ago. Other critters that have been in there include Lawnmower Blennies, Copperband Butterfly and Blue/Green Chromis. All of the aforementioned are gone due to various causes, none of which I consider directly attributed to aggression from my Maroon. The Lawnmowers seemed to be more prone to aggressive posturing and the odd chase by my Maroon than the other species, except the Blue Devil Damsel, he was definitely on her hit list, but too smart and wiley to get himself injured. He eventually expired due to some cancerous growth on his tail fin.
My hand will also get Mama Maroon into a higher state of irritability, but she's never drawn blood or taken any tissue off my knuckles, thankfully. Often the order in which fish are added to the system determine how well (or not) they co-exist, but as you can see in my case, the Maroon being one of the first, doesn't bother the Tang or Angel which were added much later. So other than relating my fish list and experience, there's not much I can add to help you with your situation. If moving rocks has little long term success, save yourself the trouble. You may just have an ornery female Maroon that will never stop harassing certain fish in your system. The only other thing you might try is pairing her up with a small male or possibly adding a BTA for her to host in, although that could easily have the opposite effect and make her even more territorial and ornery.
