I have just started my first salt water tank. I have 2 percula clowns a 6 line wrasse and a pajama cardinal. One of my percula clowns looks very sick. He is really thin and does not seem to be eating. His color has lightened and he his tail fin and pectoral fins seem to have a milky white film on them. He is not swimming normal and seems very weak. I tried to get a picture to post, but I can't get a good shot of him. The other 3 fish all seem healthy and happy. Any idea of what this might be and what I can do to save him?