Mine also does this from time to time. He'll go up for air then go back down and blow air bubbles, not sure what's happening but he appears healthy and eating so i'm not too worried about it.
Yes mine too gasp at the water surface and also spits out bubble and my water at the top side tank create bubbles at the side. Before i hav this fish there no bubbles at side. If the bubbles of the side tank cause by them is the water condition would be fine?