Preheat the oven to 400 degrees F (204 degrees C). Pat the fish fillets dry with paper towels and place on a rimmed baking sheet.

In a small bowl, whisk together melted butter, olive oil, and lemon juice. Brush the butter mixture onto both sides of each fish fillet.

In a separate small bowl, stir together the paprika, garlic powder, salt and pepper. Season both sides liberally with the seasoning mixture.

Bake flounder in the oven for 12-15 minutes, until the fish flakes easily with a fork or reaches an internal temperature of 140 degrees F (60 degrees C). (You can cook to 145 degrees F if you like, but it’s more moist and tender at 140 degrees F.) Time can vary depending on the thickness of the fish, so check at 10 minutes.

https://www.wholesomeyum.com/flounder-recipe/