In a large bowl, mix the rye flour, all-purpose flour, and salt.
Gradually add the water and melted butter, stirring until a soft dough forms.
Knead the dough on a floured surface until smooth. Cover with a damp cloth and let it rest for 30 minutes.
In a large bowl, combine the fish fillets, pork pieces, chopped onion, ground black pepper, salt, dried thyme, and dried dill.
Add water or fish stock and mix until well combined.
Preheat your oven to 350°F (175°C).
Divide the dough into two portions, one slightly larger than the other.
Roll out the larger portion of dough on a floured surface to form a circle or rectangle, depending on the shape of your baking dish.
Place the rolled-out dough into a greased baking dish or a pie pan, pressing it into the bottom and up the sides.
Spoon the fish and pork mixture into the dough-lined dish, spreading it out evenly.
Roll out the remaining dough to form a top crust.
Place the top crust over the filling, sealing the edges by pressing them together.
Cut a few small slits in the top crust to allow steam to escape.
Bake in the preheated oven for about 1.5 to 2 hours, or until the crust is golden brown and the filling is cooked through.
Allow the kalakukko to cool for a few minutes before slicing.
Enjoy your meal!