I had a 9" queen trigger in my 210 for a long time. She was always the boss of the tank, but didn't attack anyone for quite a while. She even jumped out of the tank and took a 6' fall and laid on the floor for some time undiscovered and still managed to live.
Then one day she changed. She started charging the tank when putting your face near the tank, and took two huge bites out of my maroon clown (specifically, the top and side fins of the clown, which amazingly are in the process of growing back). Even after this attack, she got along fairly well with her tankmates. I could tell she needed to be in a different tank and sold her to another guy on RC. She's much happier now in his 300 gal and apparently getting bossed around by a crosshatch (not usually that aggressive).
She paced the entire length of my tank and kept mostly to the top of the tank. QTs are open water fish so that should give you an idea of the space needs. They are great fish, just need to watch them so you can get them a new home if and when the time comes.