In a small bowl, combine the ingredients for the spicy Cajun seasoning. Stir to combine and set aside.
In a large bowl, combine the mango, avocado, red onion, jalapeño, garlic, and fresh cilantro. Add fresh lime juice and season with salt and black pepper, to taste. Stir to combine and set aside.
Sprinkle the Spicy Cajun Seasoning onto both sides of the snapper fillets. Rub gently to ensure the seasoning is evenly distributed and adheres well.
Heat a tablespoon of olive oil in a large skillet over medium heat. Place the seasoned fillets into the hot skillet and cook until they are nicely browned and flake easily with a fork, approximately 3-5 minutes per side. Cook time will depend on the thickness of the fillets.
Remove from heat and serve immediately with some of the mango-avocado salsa on top. Enjoy!