Heat up the grill while you prepare the fish.
Rinse and pat the fish fillets dry.
Add the olive oil to a large bowl, and coat the fish in the oil.
Place each fillet on a baking sheet.
Season the fish fillets with salt and pepper.
Place each of the fish fillets directly onto the already heated grill.
Grill fish on high for 10 to 12 minutes, turning for the last 1 to 2 minutes.
Use a grilling spatula to carefully get under the whole fillet and pick it up off the grill.
Serve immediately with tzatziki sauce and your favorite sides.