will mosquito fish survive the winter?

The pond is 2 feet deep ~ 500gal. I put about 15-20 mosquito fish in it
this fall. It's a new pond so I don't have anything else in it yet.

Usually our low temps. this season in Seattle are around 40-45F degrees, but
we've been having cold snaps where the pond has had a layer of ice on it for
a few days at a time during about 3 different weeks since October. One of
those weeks is this week. Overnight temps are mid 20's. Ice on the top of
the pond again.

The feeling I get from what I read is that the mosquito fish will still be
there in the spring. Really? Honestly? Is that true? It just seems so
amazing to me that I can believe it.

Or are they most likely all dead by now? Should I do something for them
like dump hot water in or break a hole in the ice even though it'll probably
be gone in no more than a week?

Thanks!
Lydia