Pond Boss Forums INTRO Questions & Observations I've had a few fish die

Here's my two cents...if oxygen were the problem, you would have lost more fish.
Follow the water chemistry.
Your well water will be chemically different than surface water.
Surface water is influenced by surface minerals in your soil. If you are in pine tree country, your soils are acidic.
Well water is likely quite different, influenced by subsurface deposits.
Analyze your well water, and your pond water. Look for differences in pH, alkalinity, and individual mineral content.
I agree with the posts for you to aerate, but not because you need oxygen. You need mixing, and processing of your existing water via bottom diffuser.
The few dead fish are an indicator of water issues.