I did a 20% water change 3 days ago. Checked the chemicals yesterday and everything is perfect. I woke up today and my feather duster had dropped all of its crown. Then i noticed that the cow fish looked like its skin was coming off and its eyes were clowdy. i gave him a freshwater dip and he looked better. but tonight i looked at the tank again and now the yellow tang looks like it has ick and the hipo tangs eyes are clowdy. i have NO IDEA what is going on! WHAT SHOULD I DO!!??!?!