1. Preheat oven to 400 degrees. Place fish, gray-side up, on work surface. Using a paring knife, make an incision 1/2 inch from the tip of the tail fin, just deep enough to remove the gray skin. Grab the skin with one hand while holding the fish in place with your other hand, and gently pull off the skin. Be careful near the fish's eye, as it is easy to damage the flesh in this area. Using kitchen scissors, remove the side and dorsal fins. Place fish, white-side up, on work surface. Using the back of a knife, scrape the white skin to remove the scales. Rinse under cold running water, and pat dry.

2. Fill a shallow dish with flour. Season both sides of the fish with salt and pepper, and dust with flour, shaking to remove any excess. Heat oil in a very large skillet over medium heat. Add fish, white-side up. Cook until a crust has formed and fish is golden brown, 4 to 5 minutes; turn fish. Transfer pan to the oven, and cook until fish is golden brown, about 4 minutes.

3. Remove fish to a platter; set aside. Add butter to the pan all at once. Cook on medium-low heat until melted and foamy. When the foam becomes golden, squeeze in lemon juice, and whisk to incorporate. Add parsley and almonds, if using, and season with salt and pepper. Pour the sauce over the fish, and serve immediately.