You can also print a picture of other tangs that look similar to the bullies and tape it to the side of your tank. I did this as well as the mirror thing with my yellow tang and it worked. Also the rock re-arrangement is a good idea. I put my tang in the sump for a few hours while I re aquascaped and then I put my blue tang in first and waited a little while before putting the yellow one back in there. My yellow tang didnt even look at the blue one. It has now been 1 year after that and they seem to like to hang out together, I have seen virtually no aggression.

