with a 500 gallon pond you are overstocked. it sounds like you didnt quarantine the
new fish before adding them. new fish bring in disease to the fish that are already
there. what are your water parameters? did the ammonia spike?
Ingrid

I'm new to this group, live in Colorado Springs and have recently built a
500 gallon pond. I stocked with goldfish, waited a month then added three 8"
Koi a freind gave me. Problem is, the goldfish seem terrified of the Koi,
not even coming up to feed anymore. The Koi arn't feeding either, maybe the
terror is mutual. Is this a normal phase? When will everyone learn to sit
down and eat together?