For the past year and a half, I have been having a problem with fish living about 5 months and then getting extremely thin and proceed to die within about 3 days. They do show signs of internal bleeding. I have had 5 fish die from this over the past year. I currently have a tamini tang, a sailfin tang, a flame angel, and two black clowns in the tank. My Naso Tang died last week. Again started to get thin then I found him dead about 5 days later. I was treating with Prazipro and he was eating it. The Sailfin is very thin and has been for about 2 months, but he still eats and does eat treated food. My Flame Angel has started to thin and is turning lighter in color. I see him spit out the food I am at my wits end. I have tried other foods, treatments, but I keep losing fish. My water parameters always come up within acceptable levels. I have been a reefer for 10 years and have never had this kind of a problem. Any suggestions would be appreciated.