My homemade Cajun seasoning blend lends its signature heat to this smoky Blackened Mahi Mahi that’s ready to serve in 15 minutes! Delight your household tonight with bold flavor and an Island-inspired mango salsa topping.

Like my Blackened Chicken Recipe, this Blackened Mahi Mahi recipe is virtually foolproof. With bold flavor, and a punch of smoky charred flavors, dinner can be on the table in as little as fifteen minutes!
I always get so excited sharing recipes from my roots like Shrimp Etouffee and my Fantastic Crawfish Seafood Boil. Specializing in the old-fashioned Cajun flavors that I grew up with, Blackened Mahi-Mahi is an infusion that’s as complex in flavor as it is simple, but very strict, in technique. This may very well be your new favorite tool in the midweek meal arsenal. Let’s get cooking!
Blackening Seasoning Mix for Mahi Mahi
Here’s an overview of the common spices you’ll need on hand along with some pro tips for cooking this delicious recipe.
Blackened Dry Rub: Like I do with every recipe, I customized my classic Cajun blackening seasoning by making a few adjustments to the spice blend. With fish, I generally like to add a bit more thyme and oregano to add some earthiness. I also like to use smoked paprika rather than sweet (or “regular” paprika) in this dish to add a little more smokiness to the mild fish.
Mahi mahi: Mahimahi, also called dolphin fish, is lean with a medium firm texture and moist flakes. It has a mild sweet taste. Look for firm, pinkish meat and defined striping to identify the highest quality fillets.
Cast Iron Skillet: The key to success is a well-seasoned cast iron skillet. A regular steel or nonstick pan will work in a pinch, but the fish may not be as blackened.
Step-by-step Recipe Guide
The full instructions and ingredient list is in the recipe card at the bottom of this post, but this visual guide often answers a lot of questions about how the recipe comes together.
- Dice/chop ingredients for pico-style topping. Stir together and allow to sit while cooking the fish. It’s easy to change the ratios to suit your tastes. (photo 1)
- Pat fish filets dry with paper towels and generously pat with Cajun spice mixture. Let sit for 15 minutes, if possible, to let the flavors soak in a little.
- Add butter to preheated HOT pan, followed immediately by the fish filets.
- Cook through until you get a good crust and the fish flakes easily. This is usually about 3 minutes one side and a minute or 2 on the other depending on thickness.
The 10 minute rule: Cook your fish at 10 minutes per inch of thickness and only flip the fish once. This works whether you’re grilling, broiling, steaming, frying or baking. For example, cook a ½ inch thick fish filet for 5-minutes—flipping it over after about 2 ½-3 minutes.
Serving and Reheating
What to serve with this fish? I usually serve with a good citrusy mango or pineapple topping or Corn and Black Bean Salad as a fish topping. Rice, smashed sweet potatoes, and Roasted Butternut Squash also make excellent side dishes. This recipe also works excellent for blackened fish tacos!
Leftovers. I love that this recipe makes exactly what you need in however much you need it, but if you do have leftovers, store the topping separately from the fish and wrap in foil or airtight containers in the refrigerator. Lasts about 4 days. Fish can easily become rubbery in the microwave, so it’s best to reheat in the oven if allowed.
Place the fillets on a wire rack set in a baking sheet or dish, cover them with foil (to prevent the fish from drying out). Heat fish in a 275-degree oven until it registers 125 to 130 degrees, about 15 minutes for 1-inch-thick fillets (timing varies according to thickness).
FAQs
Test your fish at the thickest point with a fork at an angle. The fish will flake easily and lose its translucent appearance when it’s done cooking. A good rule of thumb is to cook the fish to an internal temperature of 140-145 degrees.
Blackening is traditionally done in a cast iron skillet and there is something truly special about it with the even, super-hot heat. However, a regular steel or nonstick pan will work in a pinch, but the fish may not be as blackened, or the spices quite as deep and vibrant. The dish is still delicious though!
Like many other tropical fish, mahi mahi is semi-mild and could be described as a sweeter tasting fish. It flakes well, but it is also dense and meaty, like swordfish. Blackening mahi mahi adds an earthy, spicy combination that perfectly complements and highlights the distinctive texture and flavor.
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Blackened Mahi Mahi
Ingredients
Fish
- 1 lb Mahi Mahi fillets 3-4 fillets
- 2 tablespoon butter
Cajun Blackening Seasoning
- 2 teaspoon Smoked Paprika regular is fine too
- ½ teaspoon Cayenne Pepper This is 3 pepper spicy rating, for less heat, add just a pinch or less.
- ½ teaspoon Onion Powder
- ½ teaspoon Garlic Powder
- ½ teaspoon Dried Thyme
- ¼ teaspoon Oregano
- ¼ teaspoon Salt
- ¼ teaspoon White Pepper can use black pepper as a substitute
Fish Topping
- 1 cup Mango diced
- ½ cup Red Bell Pepper diced
- ½ cup Cucumber
- ¼ cup Red Onion diced
- ¼ cup Cilantro chopped
- 1 Lime
- White Rice
Instructions
- The key is using a cast iron skillet and medium-high to high heat. If you do not have a cast iron pan, you can do this in a regular steel pan, but it may not be as black or quite as vibrant.
- In a small bowl, combine seasonings. Pat the fish fillets dry and generously sprinkle the fish fillets on both sides with the spice mixture. Pat the mixture into the surface evenly. It's best to let the seasoning sit on the fish for 15-30 minutes if time allows.
- In a small bowl, add diced cucumber, red pepper, mango and red onion. Rough chop cilantro and squeeze the juice of 1 lime. Stir and allow to sit while preparing the fish.
- Pre-heat pan thoroghly over medium-high heat. Wait until the pan gets really hot. Add butter to the hot pan and place the fillets in the pan immediately, but don't let them touch.
- Give it a few minutes to turn black-brown with a nice crust on the one side and flip to finish it off. Cook about 5 minutes total for ½ inch thick fish (3-4 minutes one side and a minute or 2 on the other). Timing will depend on thickness.
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