In a small bowl, mix together harissa, yogurt, and salt. Rub onto fish and marinate in the refrigerator approximately 30 minutes.
Preheat oven to 400 degrees F.
In a cast iron or oven safe pan, spray with oil and place fish in pan.
Move to oven and cook approximately 10 minutes until the fish is cooked through and flakes easily.
Serve with lemon wedges.