Is this normal?

[mrcoberg]

Every day my hippo tang and sometimes by triggerfish will go to the top and gulp air and then shoot down to the bottom of the tank and release the air as they are going down . They are the only two fish out of the six I have that do this, there are plenty of live coral that produce oxygen and have a thriving ecosystem in the basement. This has been going on for at least 4 to 6 months . Any thoughts on the matter are appreciated and welcomed

 

[Reefing Madness]

Just fish goofing around.

 

[mrcoberg]

Thank you for your reply

 

[mrcoberg]

I was worried there was a O2 deficiency or something of that nature.