Can anyone tell me?

[RaeRae1]

Can anyone tell me what this is and how to cure it? I was given this tank from a friend. It is a 55 gal. I have a coraline skimmer and refusium. Some day I would like to get into a reef tank but would like to find out what is wrong with this fish before I do anything else. Thanks for looking.

 

[jp634]

could not tell ya i would take the picture to a good salt shop and have them look at it