If you have an undergravel filter it is best to keep it circulating to avoid having the area under the plate go anaerobic on you. For just oxygenation, a wheel type filter will disturb the water surface enough for good oxygen exchange to take place. There should be no need for things like air stones if that is your question. As wolfwolf said, the fish load and filter size will determine if you have enough filtration but that is a separate question.