Yeaahh, uhh. I'm gonna be a little controversional here i guess.
Overstocking has ALWAYS worked for me. With big aggro territorial fish, it's the best way to grow perfect specimens if you ask me.
My tanks have always been overstocked (except ofcourse breedings tanks, etc.)
And not a single fish of mine can you find a missing scale or a torn fin on. Not one. And i even have a large pair of breeding jags in my community.
So yes, it definatly works. But you also kind of have to know what you are doing. Every single piece of decor in the tank, be it a rock or a piece of driftwood has to be carefully positioned and thought out.
If i were you i would go with Aquanero's suggestion and add some silver dollars. 6-8 maybe (of a decent size) and see how that works out.