I have had a yellow tang (earl) for 6 months now,when I got him no problems never got ich, he's never had any diseases and has always ate consistently, I feed him once a day with nori everyday as well. He was doing good the last week, swimming around being happy, full of life, this morning checked my tank before school, earl was doing the usual swimming around the tank prior to the lights turning on, everything was fine, came home fish were all doing good. Fed the fish, he came out a little didn't eat. I thought that was a little odd but didn't think much about it. About ten minutes ago went over to take a break from homework, and I saw my tang laying in the corner on its side. He's still alive but breathing short fast little breaths. I know he's not going to make it..... unfortunately. Did tests on water quality. Everything is perfect, all my other fish are acting totally normal like nothing ever happened but within like 2 hours my tang went from happy healthy to dying. I honestly have know idea what happened. He has know signs of ich or any disease. Any help on this would be great. This has been a bad week, my delectus dottyback (Satan) kills my little goby and now my tang randomly dies. If anyone has some sort of explanation please share!