If creating the spice mix, combine the seasoning ingredients in a small bowl and mix well. Set aside until ready to use.
Pat the fish dry with paper towels and place them on a cookie tray or plate. Brush them with oil and lightly season with salt and fish seasonings.
Clean the grill grates thoroughly and lightly oil them to prevent the tilapia fillets from sticking. (Dip a folded paper towel in cooking oil and rub it across the grates with tongs.)
Preheat your grill to medium-high (375-400°F/109-205℃). If using a charcoal grill, ensure the coals are evenly lit and glowing.
Place seasoned fish fillets directly on the preheated grill grates. Cook for 3-4 minutes per side, depending on the fillet's thickness, or until the fish is cooked (internal temperature will be 130-140℉/55-60℃). Avoid flipping the fish too often to prevent it from falling apart. If possible, use a fish spatula to flip the fillets carefully.
Allow to rest for a few minutes, remove from the grill, garnish, and serve with your favorite sides.