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My folks had a trout pond and raised a hundred or so trout every summer before they went south for winter (with their freezer). My step-father would fish out the trout, remove the heads and gut them, then Mother would freeze them in bags of spring water, the fish entirely covered in 2-3 inches of ice. (It's a 2-step process because the fish tend to float.) I've always done fish that way too, because the frozen fish when cooked taste like fresh fish, not frozen.
I have an opportunity soon to get a mess of trout to freeze. However, freezing a bunch in bags or cartons of water will take far too much space in my freezer. So, here's an alternative... ice-glaze them.
Freeze the cleaned fish on a tray in the freezer; while it's freezing solid, put a large pan of water in the freezer. (It will take longer to freeze than the fish.) When the fish is solid, dip it in the near-freezing water, and put it back on the tray to freeze. Repeat as many times as necessary to build up a good covering of ice-glaze. I'm using 1/8" or maybe a bit more.
Once your fish are encased in ice, wrap them in film, freezer paper, or foil, making sure the wrapping is tight. Vacuum-sealing is great for this. Fish frozen in this manner and wrapped correctly will keep a long time in a manual-defrost freezer. A self-defrosting freezer turns on the heat to melt accumulated ice on the shelves and walls, partially cooking any foods in the process, so keeping time is much shorter for any frozen food.