Step 1

Preheat oven to 400°. Put potatoes in a large bowl. Drizzle with 4 Tbsp. oil and toss to coat. Season with salt and pepper. Line a large rimmed baking sheet with parchment paper and grease parchment with 1 Tbsp. oil. Layer potato slices evenly on parchment; season with salt and pepper. (If using a smaller fish, such as branzino, par-cook the potatoes in the oven for 15 minutes now.) Arrange half of the lemon slices over potatoes and sprinkle with parsley.

Step 2

Set fish over potatoes and rub with 2 Tbsp. oil; season skin and cavity with salt and pepper. Top with remaining lemon slices and arrange bay leaves over fish. Drizzle with remaining oil. Bake until fish is just cooked through, 40-60 minutes (depending on size). Using a butter knife or metal spatula, flake flesh off the bone and serve immediately.