What kind of fish is he? The picture is a little blurry, so I am just asking instead of guessing.
Honestly, if he is swimming around but skimming, thats not all that weird. If you are doing that as water changes, its unlikely the water quality. How long have you had the fish? Is it breathing heavily?
How big is the tank? Can you measure the water params? How long has everything been in it?
Yeah, driftwood does tint the water sometimes, but it won't hurt the fish. No worries.
I honestly highly doubt that this is about the fish getting enough o2
. You average filter does a pretty good job at mixing the air into the water. And you said you have an airstone, so I am sure you are well oxygenated.