I had similar experience as secretiveFish, fish appetite dwindled, I was doing regular water changes had ammonia spike, was using amquel to control ammonia, water was cloudy. My Powder Blue Tang got skinny, and on day 22 of treatment he was laying on the bottom of the tank not looking good. I was able to scoop him out without him even trying to escape the net. I transferred him to my 40 gallon tank and he has fully recovered looking really good/healthy/fattening up nice. I ended the treatment (Even though I planned on going 30 days) after day 22, turned on skimmer + lighting and the clowns are looking good again and eating voraciously. I'll need to wait for awhile to see if Ich returns or not.