Shhhh hes asleep!

If your talkinga about the white dot by his tail then yes, all surgon fish have these its where they get their name from. But if your talking about on the side just behind his gills its discoloration.

The white behind his gills occurs on every yellow tang (that I've seen) when the lights are turned off. When you turn the tanks lights on it goes away. I think that it acts as some type of visual signal (during night time) in its natural habitat, maybe so they can stay in a group or something like that.

ph shock for the red blob take action my frind had the same prob

white on side is not discoloration, it's part of their normal coloration... when the lights are on, the "white" area is a ligher yellow than the rest of the body, at night this area turns white... most fish change colors to some extant at night. Let me know if you have any other questions.

snoop i knew someone would mention the "red" blob. it only appears when he's asleep like the white line on his sides and also its not a red blob, its actually just a darker patch like the darker patches on his side, for some reason it appears to be reddish. During the day hes perfect.

oh thats why you posted he is asleep

hell if he looked like that awake id scream. (like a girly too)!

lol

coolfish