Combine salt and water to make brine. In a plastic or ceramic bowl, (NOT METAL) soak fish pieces in brine for 24 hours, covered, in the refrigerator.
Drain salt brine and replace with white vinegar (enough to soak the fish). Soak in vinegar for 24 hours, covered, in the refrigerator.
Make the pickle brine and cool it in the refrigerator the same day you soak fish in vinegar.
In a pot on the stove, pour 2 cups white vinegar, sugar, pickling spices, and wine. Boil and cool this brine.
In glass pint jars, layer fish and onions. Fill jars with pickling brine. Refrigerate. Edible in 1 week. Keeps for about 4–5 months refrigerated.
Cook's Notes: Any white flesh fish will do. I use the "Y" bone meat from pike. The pickling / brining process dissolves the bones so that part of the fish is not wasted. I've also used white bass, discarding the red flesh closest to the skin.