If he is not having any bouyancy issues it is not air in the pouch.
He is either pregnant or he has simply filled his pouch with water, which males will sometimes do.
I noticed his pouch is light. Many times a pregnant males pouch will turn dark for the duration of the pregnancy.
There are a few signs you can watch for if he is pregnant. Most will become very reclusive, pouch will darken as I mentioned and some will be a little more difficult to feed, sometimes needing to be target fed to be sure they are getting enough nutrition.