Mix the milk and lemon juice and let sit for 1 minute. Pour into a flat container and add the catfish, turn to coat. Place in the refrigerator for 15 minutes.
In a bowl, combine the panko, cornmeal, seasoning salt, black pepper, cayenne, paprika and parsley. Place in a shallow, wide dish for dipping.
Remove the catfish from the milk and place on a plate. Brush mustard over one side of the catfish.
Place the fish, mustard side down in the panko. Brush the other side, then flip it over, pressing gently to help the panko adhere to the fish.
Place fish in the air fryer basket and repeat. Make sure not to overcrowd the basket.
Spray all the fish with oil or non stick cooking spray.
Place in the air fryer and set for 400 °F (204 °C) for 7 minutes. When time is finished, flip the fish and spray the fish with nonstick cooking spray. Return to the air fryer and cook for an additional 6 minutes.
Remove and serve with tartar sauce and lemon wedges.