Pickled pike is a classic treat here in North Dakota, but it also boasts a practical aspect: the acid in the vinegar dissolves the dreaded "Y-bones" that make filleting northern pike such a chore.
Freeze Northern Pike fillets for 48 hours to kill any parasites like tapeworms.
Remove Pike fillets from freezer and let thaw.
Add 4 cups of the water and salt to a small pot and heat until salt is dissolved. Let this brine cool to room temperature, but preferably colder. When it is cold enough, submerge the pike pieces in the brine and refrigerate overnight.
Next, bring the sugar, vinegar, and the remaining cup of water, bay leaves, and the pickling spices to a boil. Simmer 5 minutes, then turn off the heat and let this cool.
When the pike has brined, layer it in a glass mason jar with the bay leaves and red onion. Pour over the cooled pickling liquid with all the spice and seal the jars. Store in the fridge and wait at least one week before eating. You can store the pickled northern pike in the fridge for up to 1 month.