What should we do treat the fish in our pond?
We have an outdoor pond for our goldfish. Up to a few days ago we had not lost any of the goldfish. 3 days ago we lost 1, yesterday we lost 1, and today 2. Inspection of their bodies did not indicate anything unusual except red at their gills. Looking at the fish in the pond did not indicate any abnormal behaviors.

Bill Ladmer

Water quality must be assessed, as the pH simply may have fallen below six.
Salt is a good first step in cases of this type after a water change.
Read what you can about water testing, water quality and applying salt at KoiCrisis.com
Then rephrase the question with those parameters included and a specific question.
Doc Johnson