Prepare the potatoes: Boil and mash the potatoes; set them aside.
Simmer and flake the fish: Simmer the cod fillets covered in water until it flakes easily, about 3 to 5 minutes. Drain and flake the cod with a fork. Be sure to remove all bones.
Mix the fish, potatoes, and remaining ingredients together: Mix the flaked fish, the potatoes, and the rest of the ingredients together well by hand. If the mixture is too crumbly, add another egg. If too sticky, add some more breadcrumbs.
Form the mixture into cakes and fry: Form the mixture into cakes and fry them over medium-high heat in a skillet coated with oil until nicely browned on one side, then flip them over and continue to cook until well browned on the other side.
