Easy Blackened Mahi Mahi with Cajun Dry Rub Recipe

What Makes This Recipe Great

Restaurant-quality fish can be done in your home kitchen and this recipe is here to prove it! This tender, buttery white fish is spiced with a homemade cajun dry rub made with simple spices you probably already have on hand. 

I like to serve this paleo blackened Mahi Mahi topped with sliced avocado and a fresh lime wedge. The coolness and creaminess balance out the spice, and the tart lime adds a punch of flavor. Plus, avocado is a great source of fat and vitamins. 

This healthy dinner is paleo, Whole30, gluten-free, and low carb all in one easy, 15-minute dish that’s simple enough for a weeknight, but tasty enough to be on a fish house menu! 

If you’re looking for more fish recipes to have on hand, try my reader’s favorite Blackened Salmon, these Southwest Tuna Cakes, or this Halibut with Creamy Cauliflower Risotto. All are keto, low-carb recipes that I know you’ll love!

Cajun Dry Rub

When I was first perfecting this blackened cajun seasoning blend, I started off with just 1/4 teaspoon of cayenne pepper, thinking even that would be too spicy for me. But after eating it, I decided I could handle the extra 1/4 teaspoon. A 1/2 teaspoon is just the right amount of spice for me, but if you like it extra spicy, feel free to add more.

• You’ll need a simple mix of dried spices to make the blackened seasoning: parsley, oregano, thyme, smoked paprika, cayenne pepper, garlic powder, onion powder, kosher salt, and black pepper. 

• Wild Caught Mahi Mahi Filets: Costco sells a bag of frozen Mahi Mahi fillets that are wild-caught, and so delicious! Plus they’re a great price. Make sure they are thawed and patted dry with a paper towel before cooking. You can also use fresh Mahi Mahi if preferred. 
• Coconut Oil: Or your favorite neutral cooking oil. Avocado oil or olive oil are good options as well. 
• Avocado & Lime Wedges: Optional, for garnish. You can swap the lime for lemon juice if preferred!

1. Make the spice blend by combining all the dried spices on a plate or a small bowl and stirring with a fork to combine.
2. Heat a medium-sized skillet (I used a cast-iron skillet)  over medium-high heat. While it is heating up, dredge the fish filets in the cajun dry rub, and coat evenly. 
3. When the pan is warm, add the coconut oil, and cook the spice-rubbed fish until cooked through. The cooking time will depend on the thickness of your fish. Typically about 3-4 minutes per side. The fish is cooked when it flakes easily and reaches an internal temperature of 145 degrees F.
4. Serve warm. Top with sliced avocado and wedges of lime. I love serving mine on top of my coconut lime rice or cauliflower mash.

• ​​Spice Level: 1/2 teaspoon cayenne pepper will make this mild spicy. If you like it spicier, feel free to add more. If you are heat sensitive, add less or even leave it out so it is more kid-friendly. You can also swap the cayenne for chili powder if that’s what you have on hand.
• Fish Alternative: This recipe will work for any firm fish filet. I’ve also done this with halibut, salmon, and sole. Use any wild-caught fish of your choice!

Serving Tips

• If you have the time and it works with your diet, I must insist you make my coconut lime rice to go along with this. All of the flavors together are just too good! 
• For a low-carb option, serve with cauliflower rice or mashed cauliflower. 
• You can also serve this as fish tacos which have a delicious flavor and are one of the best ways to eat this blackened fish!

Storage Tips

• Store leftovers in an airtight container for up to 3 days. Reheat over the stovetop in a skillet with a bit of oil until the fish is warmed through. 
• To freeze, wrap the cooked and cooled fish tightly in plastic wrap. Then place it into a freezer-safe container. Store for up to 3 months. Thaw and reheat over the stovetop. If stored any longer, cooked fish can have a strange texture, so be sure to eat it within 3 months.