Rinse & Dry: Begin by rinsing the whole trout under cold water, both inside and out. Pat it dry thoroughly using paper towels.

Seasoning: Brush the trout with olive oil or melted butter, ensuring you coat both the exterior and interior. Season both inside and out with salt and pepper. If you're using additional herbs, seasonings, or minced garlic, add them now. Lemon slices and herbs can be stuffed into the cavity of the trout for added flavor.

Preheat your air fryer to 375°F (190°C). If your air fryer doesn't have a preheat setting, run it empty for about 3 minutes at the desired temperature.

Place the whole trout into the air fryer basket. Ensure it fits comfortably and isn't squeezed or pressed against the sides, which could prevent even cooking.

Cook for 15-20 minutes. The exact time will depend on the size and thickness of the trout. If you have space and it's safe to do so, consider flipping the trout halfway through the cooking time for even browning.

The trout should have a crispy, golden-brown exterior. The flesh should be opaque and flake easily with a fork when it's done. If in doubt, you can use an instant-read thermometer — the thickest part of the trout should reach an internal temperature of 145°F (62.8°C).

Carefully remove the whole trout from the air fryer using a spatula and transfer to a serving plate.

For added flavor, you can squeeze fresh lemon juice over the trout before serving.