Preheat oven to 425°F. Rinse fish, make sure all scales have been removed and pat the entire fish dry. (If you find scales, just scrap them away with a butter knife).
Place fish on foil or parchment paper sprayed with non-stick cooking spray. Open the body, drizzle with olive oil, spread garlic over flesh, season with salt as desired, sprinkle parsley and then line with slices of lemon.
Close the body of the fish, drizzle lightly with olive oil and season skin with salt. Roast on a baking sheet or in a pan for about 15 minutes, until the flesh is no longer translucent. Remove from oven and squeeze the juice from the cooked lemon over the fish for serving.
Tip: I like to serve my fish with juices from the pan when it was roasting, it is packed with flavor and great for drizzling over veggies or rice.