Right. I looked at your tank journal and then forgot that you had down sized.
The Chocolate Tang is very docile and besides grazing on LR it also grazes on the substrate which is really bonus. Also it's not prone to ich like some others. Pictures don't do this fish justice. I have a mature one and he is gorgeous.
I bet your Yellow Tang will beat the crap out of any Tang that you will place in your tank. Mine did - for a day. Then things settled down somewhat. Nipped and torn fins healed quick.
Happy shopping