The filter's current was a bit too powerful, so I modified a filter sponge at the output to reduce the flow. I have read that bettas are native to slow or no moving water rivers/ponds.
The biowheel on the filter and the anacharis plants add O2. Also, betta's have a labyrinth organ so they can breath air from the surface. He seems content enough with the O2 content. I have an air stone if need be, but thought with all the oxygenators it would not be needed.
I just got Dave about 1 month ago and I believe him to be a juvenile, as he is only 2" and adults are supposed to be 3". My previous betta was in a 1.5 gallon and jumped out, things didn't work out to well for him that day. So guess who went out and got this monster of a tank (for a betta, that is.)