Curious Rabbitfish Behavior

[erndog1001]

I have a Barred Rabbitfish. Siganus doliatus is correct I think. Anyways I have a cam setup so I can view my tank. I've noticed while viewing this way That the fish goes to the corner of the tank and seems to suck air at the surface.I've had the fish for quite a while and its completely healthy. I know other fish do this But never seen it in a saltwater species until now and was wondering if anyone else had observed this sort of behavior?

 

[Marshall O]

My Magnficent Foxface also does this on a regular basis. My Midas Blenny will do this from time to time as well.