I had a Sailfin and a Naso. When I added the Yellow, Mr. Naso turned into psycho killer. I pulled him out and he spent two weeks in the quarantine tank all alone. At the two week mark, I rearranged some of the rock work in the display tank and put the Naso back in. This time the Yellow pushed him around but just enough to say "don't F*&ck with me" That lasted about a day and all 3 have been fine ever since. I should also mention they are about the same size. I would not have added any type of Tang significantly larger or smaller than what is in there already. That would just be a recipe for disaster. You might as well open the fridge and throw the 70 bucks the fish cost in the bottom of the blackworm box. It will last longer and you'll get more or your money.