Solar Powered Paddle Wheel Water Aerator is practical where there is lacking of grid electricity or saving some cost on electricity.
A fish pond without proper aerator may not produce the quantity and quality of fish as required. A pond without proper aeration is a hazard to the fish.
Without proper aerator or no aerator at all, the pond can collect or produce a lot of muck It can give bad odor to the water and fish. The older the pond, the much muckier thing you can have in your pond. The more other organisms in the pond fighting for oxygen and nutrient with the fish.
Aeration certainly improves water quality as moving water gives better oxygen.
Moving water is better at breaking down organic materials.