Grilled Whole Flounder with Cajun Garlic Butter (Gas Grill Method)

Grilled Whole Flounder with Cajun Garlic Butter (Gas Grill Method)

Grilled Whole Flounder with Cajun Garlic Butter (Gas Grill Method)

This weekend’s catch turned into one heck of a simple, flavorful dinner — a 15.5" flounder grilled whole on a basic gas grill. No fancy fish baskets, no foil packets, just a cooling rack and some backyard know-how. If you’ve got a flounder and a few pantry staples, you’re halfway to a meal that tastes like the Gulf Coast.

Grilled whole flounder plated with rice pilaf on a turquoise plate

Step-by-Step: Grilling a Whole Flounder

1. Clean and Score the Fish

To clean the flounder, make a diagonal cut behind the head and gills — when you pull the head, the guts come with it in one easy motion. Rinse well, then scale both sides of the fish. Now take a sharp knife and slice down the lateral line until you hit bone. Add crosshatch cuts across the fillet — this helps the butter and seasoning get deep into the meat.

🔪 Make prep easier with the KastKing Intimidator Filet Knife Set — sharp, well-balanced, and perfect for cleaning fish like flounder. We keep ours in the boat and the BBQ trailer.
Raw flounder scored and stuffed with butter, seasoned with Cajun spices on wire rack

2. Add Butter and Seasoning

Slice cold butter into small pats and press them deep into each cut on the fish. As it grills, that butter will baste the flounder from the inside out. Sprinkle garlic powder and Cajun seasoning over the top — we used Slap Ya Mama for a spicy Southern kick.

🧂 Want to give this flounder a Texas twist? Try it with BBQ by Biggs Texas Trail Dust — a bold Cajun-style blend with just the right heat for fish, shrimp, or grilled veggies.

3. Set Up the Grill

You don’t need a fancy smoker — we used a six-burner Monument Grill and ran the outer burners on high, center burners off, for a perfect indirect setup. That cooling rack lets air circulate and keeps flare-ups away from all that butter.

Whole flounder placed on a cooling rack inside a gas grill before cooking

4. Grill to 145°F

Maintain grill temp around 325–350°F. Check after 10 minutes. The butter will melt down into the fish, the skin will start to crisp, and the flesh will turn bright white. We pulled ours at 18 minutes right at 145°F internal — tender, flaky, and full of flavor.

5. Serve It Up

Slide the whole fish onto a plate, maybe serve it with a scoop of seasoned rice or grilled veggies, and enjoy that buttery, spicy flounder straight off the bone. Flakes apart with a fork, just like it should.

📄 Download Printable Recipe (PDF)

Got your own way of grilling fish whole? Drop a comment — we’re always open to new tricks from the backyard pros. Until next time, keep the fire lit and the smoke rollin’! 🔥

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❓ Grilled Flounder FAQs

Can I grill flounder without a fish basket?

Absolutely! We used a simple cooling rack to stabilize the fish and prevent flare-ups while allowing heat to circulate.

What temperature should flounder be cooked to?

The USDA recommends 145°F internal for fish. That’s where it flakes perfectly without drying out.

What can I use instead of Slap Ya Mama?

Try BBQ by Biggs Texas Trail Dust — a bold Cajun rub with a smoky twist that works great on fish, shrimp, and more.

Can I make this in the oven instead?

Yes! Bake it at 350°F on a rack for about 15–20 minutes. Just keep an eye on internal temp and let the butter do its work.

Do I need to flip the fish while grilling?

Nope! With indirect heat and butter in the cuts, it cooks through beautifully without flipping or sticking.

Grilled Whole Flounder with Cajun Garlic Butter (Gas Grill Method)

Grilled Whole Flounder with Cajun Garlic Butter (Gas Grill Method)

⏱️ Prep Time: 15 minutes
🔥 Cook Time: 18 minutes
⏲️ Total Time: 33 minutes
🍽️ Servings: 2
Rating: ⭐⭐⭐⭐ ½ (21 reviews)

📝 Ingredients

  • 1 whole flounder (scaled and cleaned)
  • 1/2 stick unsalted butter
  • Granulated garlic powder,
  • Slap Ya Mama Cajun Seasoning (or Texas Trail Dust)

👨‍🍳 Instructions

  1. Make a diagonal cut and remove head/guts
  2. Rinse and scale fish
  3. Cut down lateral line and crosshatch
  4. Insert butter pats into slits
  5. Season with garlic and Cajun rub
  6. Grill on cooling rack at 325–350°F
  7. Cook for 15–20 minutes to 145°F internal
  8. Serve with rice or veggies

Nutrition Facts

Calories: 220
Fat: 13g
Carbs: 1g
Protein: 22g
Sodium: 540mg
Sugar: 0g

🎥 Watch the Video