Pat halibut dry and spray with spray oil or brush on oil. Mix salt, garlic powder, onion powder, dried parsley and black pepper. Season halibut on all sides with seasoning mixture.
Air fry at 375F for 8-10 minutes - check for an internal temperature of 130-135 degrees fahrenheit.
While the halibut cooks melt butter in a frying pan and add the garlic, cook over medium low heat until fragrant about 3 minutes. Add the capers, lemon juice and lemon zest. Allow to simmer over low until the fish is done cooking.