Do not automatically assume that fish frozen in ice are dead. I was doing some research on mosquito control by fish in backyard ponds a couple of decades ago using fiberglass raceways about 30 inches deep sitting on the ground. I was late in getting the fish out for the winter one year. Numerous variatus platies, golden shiners, fathead minnows, goldfish, and koi were motionless in tight icy slush. I collected them and put them in tubs in my basement. One-half to two-thirds of them survived, even with several dying during the next month, apparently from internal injuries. The koi had a higher survival rate than two-thirds, but the other four species had about the same long-term survival - one-half to two-thirds. Those that survived may have suffered some internal injury as they tended to be short-lived after the ordeal. Most died within a year or two of the exposure, but they lived long enough for reproduction.
By the way, all but the koi provided 100% mosquito control within four days of mosquito larva introduction. The intent was to use species easily available by homeowners at bait shops, pond stores, and aquarium stores. I chose the variatus because I knew they were cold-hardy, but I didn't realize they were that cold-hardy. Their survival was slightly better than the golden shiners, fatheads, and goldfish.
Just to make you southern guys feel better, we've had several days of minus 14 and 15 degree zero temperatures during the last ten days. That's still warm compared to our Minnesota friends. My wife, Carie, and I emptied our 11 stock tanks and brought the fish indoors in October. It's an annual event for us northern folks.