I got him 3 weeks ago or so. At first he looked stressed so I I thought he has to get used to the aquarium and his room mates. He got into a tiff with a damsel first week so i removed all of my damsels. After that, my tang was doing great, eating like a pig shrim and pleanty of algea. I thought that that was the end and he is happy now. This weekend i did a partial water change. 3 days after the tang got bad. He has no signs of ick, I checked his fins and eyes all clear. It seems like his pupules got bigger or something. I have a cleaner shrim in the tank, he comes by the tang but the shrimp doesnt clean anything off of the tang. Blue tang was all active before and now he is in his hiding spot. He is laying there verticaly not on his side. Just his stomach on the rock and balances himself.. His colors are more or less difined now.. is it stress? I never had this problem before. Whats the matter whith him???