[fishoholic]

We have a 120g with a 8" sailfin, 5" yellow tang, 7" regal tang, 3" lavender tang. They all get along fairly well and they were all introduced at pretty much the same time. We tried to add a 5" scopas tang about 6 months later and our yellow tang attacked him relentlessly. Luckily within a couple of hours we were able to remove the scopas tang and give him to our friend who has a 90g. I think if you are going to have two tangs who look alike and are roughly the same size you need to introduce them at the same time. I think this helps them have a better chance of getting along. In my experience, if the fish are similar looking, and if one of the fish is already established in the tank, it is likely that she/he will attack the new one. I would recommend getting a regal or lavender tang to go with your yellow tang, because of their different shape I believe it will be easier for them to get along.