Prep the Air Fryer: Preheat to 400°F (200°C) for 3–5 minutes. A hot basket helps create that blackened crust quickly.
Mix the Spices: In a small bowl, combine paprika, garlic powder, onion powder, thyme, oregano, salt, black pepper, cayenne, and brown sugar if using.
Dry the Fish: Pat fillets very dry with paper towels. Dry fish equals better browning and less sticking.
Oil and Coat: Lightly brush both sides of the fish with oil.
Sprinkle the spice mix generously over all sides, pressing it in so it adheres. Use all the rub for 1–1.5 pounds of fish.
Arrange in Basket: Place fillets in a single layer in the air fryer basket. Don’t overlap. If your basket is small, cook in batches.
Air Fry: Cook at 400°F (200°C) for 7–10 minutes, depending on thickness.
Thinner fillets (3/4 inch) may be done in 7–8 minutes; thicker ones may need up to 10–12 minutes. No flipping is required, but you can flip halfway for extra crust.
Check Doneness: Fish is done when it flakes easily with a fork and reaches 145°F (63°C) internally. The edges will look dark from the spices—that’s the blackening effect, not burning.
Finish: Squeeze fresh lemon or lime over the top.
Sprinkle with herbs if you like. Serve immediately.