I have a small yellow tang that I have been watching all night and its freaking out! Its white bones on his tail are fully extended, he is backing into the glass( clean, no paint or algea) no reflection and is beating his tail against it like its another fish. His fins are fully flared and he is doing what I call the "vertical pre death swim" between backing into the glass and swimming tight circles. I have "essential elements" and some other chemicals,but don't feel comfortable using them. I have an empty qt tank that I could set up tonight and fill with 10g of tank water. - have checked perams and they are all good. I could do a water change and leave him in his current setting with the lights off or just chalk one up to the "fish do strange things at times" and check him in the morning. What would you do?