Solar-powered aerators are readily available as packaged deals ... lots of them ... just use google. The circular (or rectangular) tanks used at hatcheries have special needs. The stocking rate (numbers of fish or kilos of fish per m^3) in them is usually much higher than what is found in ponds and lakes. They need a high water flow not only to provide oxygen but to remove carbon dioxide, excretory waste and uneaten food particles. In some cases, it's needed to control temperature or disease organisms.
The problem with using a water pump with an intake near the bottom is sucking-in gunk. Unless the pond has a gravel or rock bottom, clogging will be perpetual problem. Even with a gravel or rock bottom, there will still be drifting or swimming objects ... leaves, twigs, fish, turtles, etc.. A grill or grate can help, but even these can become plugged. Many water pumps don't take kindly to a clogged intake. Without safety detectors, a clogged intake can destroy them.
That's why air stones or diffusers are the preferred way of aerating most ponds ... clogging with muck is not a problem. "Diffusers" is a bit of a misnomer ... they are rubber diaphragms with many small holes that release bubbles.
I've used air stones in my pond for 15 years and have been happy with them. I use Thomas air pumps that run 24/7. Only maintenance on them has been replacing the diaphragms and air filters periodically.
One problem folks encounter when installing aerators is that most rubber of plastic tubing (or pipe) floats when it's full of air. Heavy wall plastic tubing that stays down is available but expensive. I use standard wall tubing but have periodic weights in the form of short sections of metal pipe around the plastic tubing.
Again I urge anyone with a serious interest in aeration or anything else to do with ponds to visit forums.pondboss.com. There are folks on that forum who have been managing ponds for decades who are happy to give advice.
Mike in California