Fillet and skin fish and cut in small pieces. Put fish in glass jar or small crock. Cover with 5/8 cup salt per quart of fish. Cover with white vinegar. Let stand 5 days, uncovered. Drain and soak in fresh water 1/2 hour. Combine 1 cup sugar and 2 cups white vinegar and stir to dissolve. Use small jars with covers. Alternate layers of fish, sliced onions and pickling spices. Pour over sugar mixture and cover jars. Refrigerate. Let stand 1 week before serving.