As some of you know i have my 55gal tank with my baby JD 2 FM and 4 small malawi cichlids. My cousin has a 5g tank with a comet goldfish that is so big that he can barely turn around 
Anyway in this fountain pond they have a small feeder goldfish and 2 koi that are roughly 2.5-3" and it is starting to get colder out and the water is going to freeze through the winter. I was thinking of maby putting the 2 koi in my 55g tank for the winter. If not the 55g i have a spare 5g (old better tank) and a 10g sitting out of use. Do you think they would be fine in the 10g for the winter?
thx guys