The clown has zero marks/mucus or anything. Doesn't swim into the power head. Stays stationed at the rock on the substrate almost as if it's guarding something there..
It just breathes super heavily.
You may be dealing with a low oxygen issue.
Do you run a sump?
Do you have a protein skimmer?
I would recommend pointing a power head at the surface to increase agitation. Are you using a cover on the tank? If so, I'd prop it up to allow for air circulation at the surface.
