Unless extremely oversized for the tank they're in airstones are ineffective at oxygenating the water.
What you're looking for in order to oxygenate the tank are surface agitation, substrate agitaion, and plant life.
If you have live plants, check the Planted Forum for advice on adding co2 to your water. The plants will use co2 and give off oxygen.
Surface agitation can be done with an airstone, if it's overpowering. For example, an air pump made for a 50 gallon tank, will produce a significant amount of surface agitation in a 10 gallon tank. Usually, however, this is done with either a HOB or Canister filter.
Substrate agitation is pretty much only done with a canister filter, aiming the output towards the substrate.
A larger than necessary HOB filter can achieve this in smaller (<40g) tanks.
I am not saying you should rid yourself of an airstone. Many people don't like them because of aesthetics. However, you know better than we do if your fish like them. For example, I once had clown loaches, oto cats, and even a pleco that all loved to swim downwards into the bubbles. It's a bit of fun for fish who otherwise can end up with rather dreary lives in a much smaller than natural environment.