I figure Bettas didn't need air filters but I wondered if it would stress them out if the water didn't have enough oxygen and having to go to the surface to breath alot. I'm also planing on investing in some java or willow moss, or some type of plant so the Nitrate and carbon stays low and I think plants do emit oxygen. Plus I don't have to worry too much on the fish ripping his fins as much as I would with fake one. Well thats alot of help I am just waiting for next paycheck before I purchase a tank. I certainly hope I don't get bitten by the betta bug, I don't have alot of room to place them all.