When the water cools down and the days get shorter as we move into winter solstice, the Koi will stop feeding and gradually go down to the deepest part of the pond, and hibernate until spring brings warmer temps and longer daylight. Daylight’s their primary factor in activity. They have a built-in clock, as do all animals/fish/reptiles etc. All species have it.
http://psychology.about.com/od/statesofconsciousness/p/BodyClocks.htm
How do you stop their pond from freezing over?
Thanks! I’ve been looking on YouTube for some how-to’s.