It's just dissolved air in the new water. It will dissipate within a day or so.
f you don't like it, use something like a turkey baster and squirt water along the insides of the tank. That will get rid of it.... Or you can age the new water for a day before doing the water change. You'll still need to use Water Conditioner to remove the chlorine, chloramines and heavy metals, but the aging will give the dissolved gases time to dissipate, which means they won't cover the sides of the tank.
My guy gets the bubbles on him when he swims along the side of the tank. They don't stay long. If they remain on your fish for a long time, let us know, as there may be something else going on.