What about putting 3-4 layers of newspaper or paper towels over the fish and using a vacuum packer? Most people have a foodsaver or similar units nowadays.
That would work but I frown on newspaper as it sucks the moisture out of the fish even if it's wet initially. The foodsaver material is great but the seals are notorious for breaking loose after handling.
Strangely I've had people wrap a fish in wet newspape, and than seal rally well in a garbage bag with all the air pushed out, and the newspaper in time ends up dry as a bone along with the fish. Apparently the garbage bags are not 100 % leak proof to open air. If you ever try and put water in one you'll quickly find out that is true.
