Recently one of my mature yellow tangs has been acting wacky. One morning I went to feed them and I noticed that one was just hanging out at the top on my tank, not swimming, not eating, and barely moving.... but he IS alive. It has no obvious illness...such as ick, red spots, popeye etc.... he's been doing this now for about a week and half..... and still has not moved from that spot. Any ideas??????? Thanks!!!!!