heat, predators maybe? a cat can sure scare the koi out of sight literally.

Lyle

I agree with the other post.. my fish do the same as our temps are 100 degrees everyday.. plus fish get spooked by predators too.. I wouldnt worry to much.. maybe put up a net? My koi come up and welcome me everyday about 7pm as the temps are down and they are ready to eat...

Do you have a lot of debri on the bottom of the pond? You may have to clean it out. Can make toxins. Did you check your water?

I know it has been a while since this was posted but I am just going to horn in. Do you have some new shrubs or trees near the pond? They could be casting shadows that cause the fish to think there is a predator. Or there could actually be a predator such as a heron that keeps them on guard. Have you found out what was wrong? Sandy

Scared by a heron or raccoon or just feeling too exposed. Fish like plant cover...

My largest Koi stays on the bottom and hasn't eat Is there something wrong with her?