A mate was giving up reef keeping so he was selling all his livestock and equipment. He actually told me it was a yellow tang

but I guess lemon peel is close enough, when he said yellow tang I wasn't going to buy it, but when I saw the size and colouration I just couldn't resist.
It was highly stressed when he tried to catch it, colouration went very poor, but thankfully it seems to have settled now, well apart from establishing the heirarchy with my yellow tang.