Originally Posted by nikki_kaiser
The fist yellow tang I ever had did this as well. He was in a big tank that had been established for at least a year. Your nitrates need to come down if you can. Just do a water change. What were you feeding him? Did your LFS
QT him for a while? This will sound odd, but when he died, were his gills a little red? Did he sit at the bottom and lean up against anything or did you notice? Tangs are prone to septicemic infections which are bacterial infections ( this would be the case if you see what looks like broken capillaries through the skin or gills) and parasites. They graze a lot and for the most part eat algae but will also eat meaty foods...but they can't live on the meaty foods alone. You can tell if its not eating enough or getting proper nutrition if you can see its stomach. If you look up a picture of a fat healthy tang, you'll see the difference. Let me see if I can find something to copy and paste rather than typing all this out! LOL!
Here's a tidbit of info. This may or may not help.
Surgeonfish and tangs are continuous feeders and they need to be provided a proper diet. They are susceptible to nutritional disorders which may cause color loss and LLD (lateral line disease). Supplementing their diet with the addition of vitamin C to their food or adding a vitamin supplement directly to their water can help to avoid or aid in reducing these ailments. They are also susceptible to bacteria resulting from organic buildup which deteriorates water quality. Consequently they will need vigorous filtration, protein skimming, and regular small water changes.
Many of the Acanthuridae members are very colorful, active, and attractive to aquarists. But they do not produce as much skin mucus on their bodies as other fish and can be susceptible to diseases such as Marine Ich and Marine Velvet. Surgeonfish are definitely a candidate for quarantine when you first receive them. They can be treated successfully with medical care or copper drugs, but because they have an important microfauna in their digestive system, prolonged or continuous use of a copper treatment is not advisable.