Yellow thing with white dot

[Rolo1990]

sorry yellow Tang (dam spell check)

Hi guys I’m new to all this I’m just having a problem I just picked up a yellow tang on the 17th and I’m noticing a white dot on the side can someone tell me what this might be what what should I do

Chris

 

[Rolo1990]

 

[Rolo1990]

And it keeps trying to rubbing itself on the rocks and the sand

 

[Rolo1990]

I have more pictures now it two dots