I went to a seminar here in central Texas a couple of years ago and the biologist made a good point. He said that if there is enough wind to turn a windmill, then there is enough ripple on the water to get the oxygen required for the fish. Water can only hold a very small amount of oxygen even if you shoot it up 100 feet and let it fall back. Of course he was an Aggie from Texas A&M so take it from there... ;\) . Anyway he said windmills for oxygen was sort of an effort in futility.