Good Idea Pufferlover!
When I first put my dogface in my tank, I netted him trying to get him in the water fast. As soon as he hit air, he fuffed up like a baseball. I was very concerned as he thrashed around on top of the water like a wind-up toy. He expelled most of the air in a few seconds and did make it under water. He had air trapped in him for about 2 days before he managed to get rid of it himself. He has been fine since then.