Pre-heat broiler on high. Line a broiler pan with foil and spray with cooking spray. Season fish with Cajun seasoning and salt. Arrange prepared fish filets in a single layer and broil until fish is golden brown and flakes easily with a fork, about 6-8 minutes.
While the fish is broiling, prepare mango salsa by tossing together all ingredients in a medium bowl. Season with salt and pepper to taste.
Remove the fish from the broiler pan to a plate and flake into bite-sized pieces with a fork.
To prepare the corn tortillas, heat canola oil over medium-high heat in a large non-stick pan. Using tongs, quickly toss the tortillas in the warm oil about 30-60 seconds per side and move to a plate lined with a towel. Cover the tortillas to keep warm and continue until you heat all 12 tortillas.
Divide the fish between the tortillas and top with mango salsa to serve.