Fillet the fish (leave the skin on), then make a few light relief cuts in the skin. Lightly brush oil on the skin side, turn over to the flesh side and season with salt, pepper, garlic and a touch of cayenne pepper. Toss the fillets on a medium-hot grill, skin side down, and cook for about 6 minutes or until the skin is crisp. Flip the fish and cook an additional 3-4 minutes. Remove from the grill and let rest 5 minutes. Just before plating add a few squeezes of lemon juice and serve.