Help ID black blotch on purple tang

Just noticed this today - I have had the purple tang for a few weeks now - inherited it from a friend which had a tank leak. Wondering what this black spot is - Hard to see in pics but it is in the middle of the body between the rear yellow tail and side fin. Any ideas??? The tang is acting/eating fine and does not seem to be bothered by it at all.

Thanks for any help!!

 

I think that's just the coloration...

 

Can be. It also might be the start of HLLE. My lavender tang starts off with discoloration and then it progresses into sores. I'd make sure to soak his food in a vitamin supplement like selcon.

 

Beautiful fish! I would take ingtar's advice to be on the safe side.

 

Thanks for the advice - I will start soaking both the nori sheets and food tomorrow.
With HLLE, could that be from the move from tank to tank and the stress or is that something that is genetic and just happens?

 

Yeah, but I'm also pretty sure it might just be stress from moving tanks. You see that alot more with other fish, but zebrasoma will get pale and/or blotchy from stress. IF it is HLLE good diet soaked in vitamins is a good hedge.

I like to treat for the worst possible cause first since this can't be bad for him anyway.