Back in the late 80's I built a thing for the neighbor that was just a wood frame with corrugated tin on top that we punched full of small holes. We ran the discharge of a 2" pump across it for aeration. Worked pretty good -like heavy rain.
When traveling through Ms I noticed lots of the catfish farmers were aereating there ponds with an implement, I guess that was homeade hooked up to their tractors. Just backed down to the pond looked like a long shaft with a propeller.