Hey guys... this is my emperor angel (marine fish). Just over the last 2 days or so, its developed some white spots which look like lint which you find collecting on your black clothes on it. If you look at the very bad picture (its always excited when I go near my tank, anticipating feeding)... 2 spots on the caudal fin, one on its left pectoral fin, 2 o its dorsal fin:






What should I do? Is it some disease? It behaves normally with no other symptoms. Is a freshwater dip recommended?