Season each fillet with 1/2 teaspoon of Old Bay Seasoning and 1/4 teaspoon salt and place the fillets skin side up on a work surface. Divide the crabmeat filling evenly among the centers of the fish fillets and, using your hands, roll the fillets to encase the filling. Secure with a toothpick, if necessary. Place the fillets, seam side down, in the prepared dish and top with lemon slices. Sprinkle the remaining 1/4 cup of the cracker crumbs evenly over the top of the fillets. Drizzle with the melted butter. Using oven mitts or pot holders, place the baking dish in the oven and bake until lightly golden and cooked through, about 20 minutes.