Preheat the grill to medium-high, or 400 degrees Fahrenheit. Brush olive oil on the grill grates to prevent the kingfish from sticking.
Brush the kingfish with the rest of the olive oil and season the steaks with salt and pepper to taste.
Place the kingfish steaks on the grill and cook them for eight minutes on each side, or until the kingfish is cooked all the way through.
Take the kingfish fillets off the grill and allow them to rest five minutes before you serve them. The resting time allows the kingfish fillets to reabsorb some of the hot juices, which will make the kingfish fillets more juicy as well as prevent them from falling apart when you serve them.