This tang presents a little different than the others that died. They had a white fuzz on them. Velvet? I don't have great pics of those fish with it, they were hiding. First the Powder brown and another similar tang went down fast after showing some dark spots (larger than black ich, more like flat blotches, a bit subtle to see) then they got this white fuzz on them. They died within hours. Then this morning the Clown and this pictured blue tang died later that morning. This blue tang had no visible symptoms yesterday. Whatever it is moves very fast and is decimating my fish. It's really sad to watch. Anyone know what it is?