Combine the lemon juice, bay leaf, thyme, oil, salt and pepper to taste in a shallow pan. Add the fish and marinate for thirty minutes, turning once. Drain.
Place the fish on the broiler rack and broil for ten to fifteen minutes, or until fish flakes easily when tested with a fork. Turn once as it broils. Transfer fish to a hot platter. Sprinkle with melted butter and garnish with lemon slices.