Clownfish not eating or active much

[aaltayeh]

Hello, I have had a pair of clownfish for past month and half. One of them for the past week has not been moving much or eating. No lesions on the body. Please see attached photo. Levels with Red Sea kit:
Ammonia- 0
Nitrate - 5
pH 8.2

Salinity 1.025

I have set up a hospital tank, but concerned if take him out will get more stressed as well as not sure what to medicate with. Ideas much appreciated.

 

[4tanks]

Looks like it's got hole in the head starting to me

 

[aaltayeh]

I think that’s been there for a while. Parasite?