Naso Tang - White Coloration at the Base of Tail

[mc5120]

I have a Naso Tang, for a little over a year, and recently I noticed a white band on both sides of his body at the base of his tail. The band appears to be under his skin and does not look raised. Other than this white band he seems happy and healthy. He eats daily and does not appear stressed. No new fish have been introduced into the tank for about 3 months. A water change was done less than a month ago and the water quality seems good. I have not quaranteened the Naso Tang nor have I treated the tank with any medication because all of the other fish in the tank appear healthy. Has anyone ever seen something like this? I am trying to get a clear picture to add to this post.

I am new to this forum and any help or advise would be appreciated!

[leebca]

A picture or a few pictures will be needed. If you have difficulty posting photos, you may have to post a few more posts or for more info on handling photos, request help from inside the Photo Lab

Your post would imply nothing is wrong but what you see. However it is a fact that something is wrong, if what you see isn't supposed to be there. By this I mean, those things you think are okay are in fact not. I suggest you perform all the water tests and provide us with the test results for:
pH
temp
sp. gr. or salinity
ammonia
nitrites
nitrates
phosphates
alkalinity
calcium
magnesium

and then more information about your system AND fish. This is a list of questions to answer along with the photos:

How old is your tank? When did it originally cycle?
What is the size (dimensions and gallonage) of your aquarium? Does the gallonage include the volume from the sump and any refugium?
Do you use carbon, skimmer, mechanical or other chemical filtration?.
List all specimens & sizes in the tank (fish, inverts, corals, clams, snails, crabs, shrimp, etc.).
Do you use a quarantine tank and procedure?
Foods you use and feeding schedules.
What is the length of this fish?
Do you use any vitamins? Fat additives? Any elemental or other additives? Please list all.
Do you see any of the following in your system: hair algae; micro algae; cyanobacteria growths (red slime algae); dinoflagellate (zooxanthellae) growths; brown algae; diatom growth; slimes; off-colored patches on rock or substrate that are not coralline; etc.?
Water changes (how much and how often).
What is your source water? (Tap water, RO water, DI water, RO/DI, distilled, etc.)
List what you added or taken out of your aquarium system (living, decorations, and equipment) during the past 6 weeks.
Maintenance schedule. What have you done lately?

As you can see, in order to provide you with the best reply, we will need much more information. . .and photos. Whatever questions, information, or data you don't provide diminishes the quality of our help/