Help! Strange white stuff on zoa polyp

[Gil2Gil]

Hey,

 

All my water perimeters are perfect, nothing has changed. Except adding a fish and shrimp.

 

But tested my water today after a water change yesterday and I'm still at perfect.

 

This frag has been growing the most, almost a polyp a week. What is this algea? Fungus? On the polyp?

 

It's still opening, just has this weird stuff on it now.

 

Thanks for the help!!