Preheat a broiler to its medium setting and line a baking sheet with foil. Grease the foil lightly with 1 tablespoon melted butter.
Season the fish all over with 1 tablespoon salt, then transfer to the prepared baking sheet. Set aside for 20 minutes.
Meanwhile, in a small bowl, stir together the breadcrumbs, parsley, thyme, orange and lemon zests, the remaining 1 teaspoon kosher salt, and the remaining 6 tablespoons melted butter.
Sprinkle the breadcrumb topping evenly over the fillets, then broil until the topping is browned and the fish flakes when the center is poked with a fork, 4–8 minutes.
Serve with the citrus wedges on the side for squeezing.
