Line a 9" x 13" baking dish with parchment paper. Place the fish fillets on the paper.
In a small bowl, combine the olive oil, onion powder, garlic powder, and paprika, and mix well with a spoon. Brush this mixture over the fish, coating each fillet completely.
Bake the fish for 20 to 25 minutes or until the fish flakes easily with a fork. Insert a fork carefully into the fillet, and twist gently. The flesh should flake easily into pieces without much effort on your part.
Meanwhile, combine the avocado, cherry tomatoes, olives, lemon juice, and parsley in a small bowl. Place the fish on a serving platter then spoon the avocado mixture over the fish, and serve immediately.