Great price op. Good advice from other posters.
Remember when it starts to freeze out side and pond temperatures drop the fish metabolism slows down kind of hibernate, bring you fish indoors, put then in a box and in the airing cupboard. In the spring they will be well rested and ready to go back out. Or, break up the ice to make somewhere for the gasses to be released, keep water flow flowing or air stone to keep water bellow the ice oxygenated.
Below-freezing is frozen, that seems a bit unlikely for a water based creature unless they can be reanimated upon defrost... I'll test with some fish fingers and report back.
We have the grand half moon of this, it is beautiful
Goldfish can survive below-freezing temps, they just need an air stone and some of the ice cover to be broken to allow harmful gases to escape.