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.
