Put an oven rack in the center of the oven. Preheat the oven to 500 degrees F. Spray a heavy baking sheet liberally with vegetable oil cooking spray. Set aside.
Put the buttermilk into a large bowl. Add the fish strips, stir to coat, and let stand for 15 minutes.
In a medium bowl, stir together the Parmesan, bread crumbs and salt. Remove the fish from the buttermilk, allowing the excess to drip back into the bowl, and dredge in the bread crumb mixture to coat completely, pressing to adhere. Arrange the coated fish in a single layer on the prepared baking sheet. Lightly drizzle with olive oil and bake until golden and crispy, about 14 minutes. Cool slightly and arrange on a serving platter.
In a small saucepan, heat the marinara sauce over medium-heat until warm. Transfer to a small serving bowl. Serve the marinara alongside the fish sticks as a dipping sauce.