Rinse the fish and place it in a bowl. Add enough cold water to cover. Chill overnight, changing the water several times.
The next day, drain the fish and transfer to a large saucepan. Cover with water, bring to a boil, and simmer until the fish flakes easily, about 15 minutes.Drain and cool. Flake the fish, discarding any bones.
Mix in the fish and potatoes. Whisk the eggs, the 1/2 teaspoon salt, and the 1/2 teaspoon pepper in a large bowl to blend. Add the egg mixture the skillet.
Cook over medium heat until the eggs are softly set, stirring occasionally, about 3 minutes. Transfer onto a platter.
Garnish with the olives and the parsley.And serve with some salad.