well now that lava fishing has became possible in the spiral I believe it should also be possible to ice fish. although there aren't many places covered in ice I still believe there should be ice fishing. there can be a fishing spell called "heat wave" that is used to melt the ice to fish in.
I mean a completely frozen lake that has to be melted to be able to fish in.
Shhhhh.... don't give them any ideas. It's another spell we'd have to use energy for. And really it would only be for aesthetics because it would basically be just lava fishing in a different color. It would give them reason to add new fish though and I'm all in on that.