Thought I'd try again with a Yellow Tang. He's been in quarantine since buying him 2 weeks ago, a few days after he arrived at the store. He's been eating fine (mysis 2 x per day and nori) and acting normal until this a.m. He wouldn't eat, is breathing heavy and currently swimming in the current of the filter. Although, I did see him pick at the nori a while ago. He's in a 10 gal tank w/only a hang-on filter w/firefish who is acting normal. I changed 3 gal water this afternoon. I dropped the water down to get more agitation, thinking maybe he's not getting enough oxygen in the water. I tested nitrate -- very low. pH is just a bit low -- 7.8 as opposed to 8.0. He's got no spots or marks. My not-so-knowledgable husband thinks it's because he's in such a small tank, since Yellow Tangs are such active fish, which I suppose isn't out of the question, but do I dare move him like his is. I'm thinkin' not. Anybody?