Serious Fish Keeper

Hey! I live in Mid-Michigan and I love my Comets and Koi. We are
raising them in a pond on the back of our property. Sometimes, we
harvest some and put them in tubs and share them with other
people.....I have even sold a few, very few.....

During the summer, I have an above ground 'pond', using the term
lightly. It's a 3 foot deep freame lined with a pond liner....I take
my personal fish out of that 'pond' and put them in an aquarium in the
house....Do I have to do that? Would they come to harm if left all
winter in that container? I know so little but I would never bring my
Comets to harm.....

Can we really get some knowledge here???

Thanks and God Bless,

Sunny