Preheat air fryer to 375 degrees F for 5 minutes. Place a piece of parchment paper into bottom of basket with fish on top.
Lightly spray tops of fish fillet(s) and sprinkle on seasonings with lemon slices on top of that. Air fry for 12 - 14 minutes (adding a slice of butter on top during the last 2 minutes) or until fish is cooked thru, reaching 145F. (timing will vary depending on how thick your fillet is)