I noticed that there wasn't any recipes for pickled fish in this forum. So here's one that I use and really like. Finished pieces are firm and sweet/tart. You can use any fish really, but most commonly pike and sucker are used because the bones are disolved in the brine. I also use bass.
Starting Brine Phase 1: 1 Cup Salt per Each 1 Quart Water. Fish pieces soak for 2 Days. (Make enough of the brines to cover all of the fish)
Vinegar Brine Phase 2: Drain starting brine - Do not rinse fish pieces. Soak in White Vinegar, completely covered for 24 hours. After 24 hours, Drain Vinegar-Do not rinse fish pieces.
Finishing Brine Phase 3: Mix 4 Cups White Vinegar, 3 Cups Sugar Heat to dissolve Sugar - Let stand until cool Add 1 Cup Sweet White Wine 1/4 Cup mixed pickling spice. Let mixture cool thoroughly before adding to fish. (I make this brine when I start phase 2, that way the solution picks up the flavors of the spices sooner so you can eat it sooner) Layer fish pieces and sliced onions in jar and cover with pickling solution recipe leave covered with pickling solution and let soak for 5 days before eating. I pack in pint jars. Fish will last for several months in refrigerator.
I generally start sampling on day 2 or 3 of the last phase. Excellent!