An easy, pan-seared Blackened Mahi Mahi recipe. Crispy fish coated with a mild cajun dry rub and served topped with avocado and lime wedges. Full of flavor, yet still light in calories, paleo, Whole30, low carb, and gluten-free! From prep to plate in only 15 minutes!

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!

Ingredient Notes

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.

Blackened Mahi Mahi

  • 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!

Recipe Step by Step

a hand dredging a mahi mahi filet in cajun dry rub
  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.
an overhead shot of a blackened Mahi Mahi fillet on a bed of rice topped with avocado next to broccoli florets and a lime wedge.

Expert Tips

  • ​​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. 

Recipe FAQs

Is blackened fish healthy?

Yes! With just a few simple spices and a bit of oil, this blackened Mahi Mahi is a healthy, low-carb, low-calorie meal with tons of protein, healthy fats, and other nutrients. It is also lower in mercury than other popular fish. 

What kind of fish is a Mahi Mahi?

Mahi Mahi is dolphinfish. Not related to Dolphins in any way, it’s a white fish that is found in the Atlantic, Gulf of Mexico, and the Caribbean.  

What does Mahi Mahi taste like? 

It has a mild flavor, with a taste and texture similar to halibut and swordfish. 

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Easy Blackened Mahi Mahi with Cajun Dry Rub

An easy, pan-seared Blackened Mahi Mahi recipe. Crispy fish coated with a mild cajun dry rub and served topped with avocado and lime wedges. Full of flavor, yet still light in calories, paleo, Whole30, low carb, and gluten-free! From prep to plate in only 15 minutes!
5 from 16 ratings

Ingredients 
 

Blackened Cajun Spice Rub

Blackened Cajun Mahi Mahi

  • 2 6-oz wild caught Mahi Mahi** filets, thawed and patted dry
  • 1 tablespoon coconut oil
  • 1 avocado, sliced
  • lime wedges for serving

Instructions 

  • Make the spice rub by combining all the dried spices on a plate and stirring with a fork to combine.
  • Heat a medium size skillet over medium high heat. While it is heating up, dredge the fish filets in the spice rub and coat evenly. When the pan is warm, add the coconut oil, and cook the spice rubbed fish until cooked thru. Cooking time will depending on the thickness of your fish. Typically about 3 to 4 minutes per side.
  • Serve warm. Top with sliced avocado and wedges of lime. I love serving mine on top of my coconut rice.

Notes

Expert Tips

  • ​​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.
  • 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. 

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. 
Calories: 285, Total Carbs: 9g, Protein: 25g, Fat: 17.9g, Fiber: 5.1g, Net Carbs: 4g
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