Azure Damsel - Any idea what is on him?

[nycjwi]

Just received this Blue Damsel on Friday and this white thing on the side of him is getting bigger.
Any idea what this could be. He is acting normal and eating.

 

[sunken3]

the pic is a bit blurry... if its a parasite I would try and catch him and dip him.

 

[sunken3]

also it could be a polyp growth (again hard to tell).