Shy Koi fish

Answer 1

I can't answer this question except to add that I tried the solution of adding goldfish (which I never knew to be shy fish), turns out the koi have made them shy too, so now all the fish hide under a plant in corner of pond. :(

Answer 2

you should add guppies or feeder goldfish that are just a couple of cents at you LFS to your pond.  They would encourage your koi to eat when you are there because your koi would see the other fish eat.  I used to have shy koi (championship bloodline) and it always get spooked when I'd go feed them but when i just went to get a couple of the feeders in a couple of days my koi just started to be more active and more revealing.  good luck