Is one dying?

[paul01]

There right next to each other why does one look like it's dying?

 

[twilliard]

I would have hope for it. It isn't too bad yet.
These guys love water that is more on the "dirty" side

 

[paul01]

Did a water change yesterday maybe that's why

 

[jsker]

What are you feeding the tank? I feed my corals a mixture of reef nutrition products and as @twilliard stated the water might be to clean.
How old is the tank?
where are you Po4's and No3's at?
and while I am asking
Ca
Mg
Alk
Ph

 

[Nihilus]

I wouldn't worry too much about it. Xenia can be a very temperamental coral sometimes.. Assuming your parameters are within reason it should bounce back to normal in no time.