Bring vinegar, sugar, and pickling spice to a boil. Simmer 5 minutes; cool.
Fish and Contents
Fillet fish and freeze for 48 hours to kill parasites.
Thaw and cut into 1-inch square pieces.
Place fish into large plastic, glass, or pottery container. (We use gallon glass jars.) Add canning salt and cover with white vinegar. Refrigerate for 5 days. Stir or shake the jar occasionally.
After 5 days, remove fish from jar and rinse well in cold water. Let fish stand in fresh cold water for 30 minutes.
Layer fish in jars alternately with sliced raw onions and peppers (optional). Cover with cool pickling solution; refrigerate.
It should be ready in 4 or 5 days; keep refrigerated. Recipe makes 1 quart and should last about a month in the refrigerator.