Let's back up, how long have you had him and what are you feeding him. Make sure all tank parameters check out. Did you release him under water, they will gulp air and that is bad, as they have a hard time expelling it. Him returning to the top may be him trying to release air, rather than gulp it. Does his stomach look spongy and/or does it seem like he is somewhat buoyant. If this may be the case, you can try and burp him.
A bit more complicated and serious response. Anglers are still very much a mystery, and many times long term success is more luck than not. They don't respond or indicate how other species would. Him gulping air is not normal and gulping air in itself would cause a problem. This type of activity in some other species could indicate parasites such as flukes. Treatment of any kind usually doesn't end well. If you've fed him well and he's still overactive, this could also point to flukes. Because it mostly ends badly, I am very reluctant to offer treatment advice. For now, as long his tank parameters check out and he is eating, I would let it ride.