MakoMike
Angler
Got a small, surplus -80 °C from work years ago, which is -112 °F, but I keep it at the "crossover point" where both scales meet, at -40 ° so yes. I use this to freeze all of my fish and then transfer to a conventional freezer.
In a pinch, one can always get a chunk of dry ice, put it in a cooler with a cookie sheet on it and freeze the fish. The ice will stay for 2-3 days in a "Omaha Steak" styrofoam cooler and probably much longer if you have a Yeti-type one. Just make sure you do this in a well-ventilated area!!
I know, the recommended time is 72 hrs...
Good for you! Use the small one for three days. I don't know that I'd trust the dry ice work around without a thermometer in it to make sure it gets low enough. Coolers vary a lot in their ability to keep cold in.