Fluke or Flounder - What is the Difference

What's the Difference Between a Fluke and a Flounder?

Fluke and flounder are terms often used interchangeably, but they refer to distinct species with notable differences, which is crucial for fishing enthusiasts and culinary experts. Flounders encompass a broad family of flatfish, including various species like the winter flounder, summer flounder (commonly known as fluke), and others, each with unique characteristics. Fluke refers explicitly to the summer flounder, a species prevalent along the Atlantic coast of the United States, renowned for its distinct flavor and culinary versatility.

One key distinction between fluke and other flounders lies in their physical characteristics. Fluke are unique in that they typically have both eyes on the left side of their body, a feature known as ‘ocular asymmetry. ‘

This unique adaptation aids in their identification and is a critical aspect of their biology, influencing their habitat and behavior. Fluke are also known for their larger size and more aggressive predatory behavior than other flounder species, affecting their distribution and anglers' fishing techniques.

From a culinary perspective, fluke is not just another fish but a delicacy prized for their delicate, white flesh and mild, sweet flavor. This makes them a preferred choice for various recipes, from sushi to classic pan-fried dishes. In contrast, other flounders offer a different culinary experience, with their firmer texture and unique taste profiles, adding diversity to various culinary traditions.

Understanding these differences is essential for sustainable fishing practices, accurate species identification, and appreciating the unique qualities each brings to the table. This article delves into the specifics of fluke and flounder, exploring their biological, ecological, and culinary distinctions to provide a comprehensive overview for enthusiasts and professionals alike.

My Girls First Fishing Experience

One of the fun adventures my girls had on our vacation this year was going sea fishing on the commercial fishing boat Miss Avalon out of Avalon, NJ.  My wife was in charge of this particular outing as I am strictly a bay fisherman - I leave the surging swells to those with cast iron stomachs.

Turns out my wife doesn't have one either, but that's another story!  You can read about their adventure at My Daughters' Catch of the Day

Both girls caught fish out on the Miss Avalon. My older daughter Nell's fish was large enough to take second place in the boat's pool. The first prize was cash, and Nell got a free fishing excursion to accompany her one-pound sea bass.

Maddie, the driving force behind the deep sea fishing trip in the first place, ended up with a ¾ pound flounder.  Or was it a fluke?  Either way, if you've never seen one up close and alive, it is a most...unfortunate-looking fish.

Early Life

Flukes and flounders are types of flatfish.  That means that, while they started life swimming upright, they lay on either their left or right side during the larval stage, and the eye facing towards the bottom migrated to be top-facing.

So, some flat fish are right-side-up (their left eye migrated to the right side), and some are left-side-up, meaning their right eye migrated to the left side.  What makes a particular fish turn into a left-side or a right-side fish?

And what makes a "normal" fish evolve into a flat fish?  I have no idea about the former, but I'm sure the latter adaptation was for camouflage while hunting for food.

The top side of flatfish is mottled and dark, making them blend in well on the ocean bottoms. As they are bottom dwellers, this is a very good thing as they can surprise their unsuspecting prey.

All Fluke Are Flounder, but Not All Flounder Are Fluke

Generally speaking, left-side-up flounders are flukes and right-side-up flounders are called flounders.  That sounds easy enough to remember, but it gets worse.  Flukes are also called "summer flounder," and flounder, or right-side fish, are called "winter flounder."

It also turns out that of the 500 plus flatfish species, five are all called flounder. It's good to know there is a difference, but I would be hard-pressed to taste the difference between a fluke and a flounder.

Four of the five flounder species are found in the Atlantic: summer flounder (left-side-up flukes), winter flounder, southern flounder, and European flounder.  The fifth, the Japanese flounder, is found in the Pacific Ocean.

Unless you are studying fish biology, and I'm certainly not, I think the main thing to remember is that all flukes are flounders, but not all flounders are flukes. And all flounders are tasty.

Fluke & Flounder Fun Facts

I did find out some fun facts about flounder and fluke, though, no matter what name you call them.  Because they are so flat, large flounder and fluke (at least 8-10 pounds) are sometimes called doormats or snow shoes. Finally, something about these fish that makes sense!

Another fun fact is that summer flounder and winter flounder are aptly named.  Summer flounder (fluke) winter off of the continental shelf and only come into the bay (to be caught) in the summer.

Winter flounder comes into the bay in the fall and stays through the winter until the spring.  Fluke and Flounder don't like to stay around each other very much.  It could be because Fluke has teeth and Winter Flounder doesn't but don't quote me.

As to weird names, I usually think of a fluke as a freak occurrence and flounder as a verb meaning wobbling about without a way to steer. One possible root word for fluke is the old German word flah, meaning flat.

I'm still not sure how something flat can also be a freak occurrence, but I don't guess it's every day that a fish's eyes migrate from one side of its head to the other.

As to the name flounder, it comes from the Dutch word flodderen, which means "to flop about."  Using that definition, all fish flounder when caught, but flounders can flop about on the bottom of the ocean, kicking up sand to cover themselves, as rays do.  Also, because they swim sideways, it can look like they don't have a very good way to steer themselves.

No matter how they look or swim, flounder is tasty when cooked. Here's a recipe for broiled flounder in lemon butter, and be sure to check out Pan-Fried Flounder with Potatoes and Parsley. This is how my mom prepared fresh flounder for us as kids.

📖 Recipe

Print Recipe

5 from 1 vote

Broiled Flounder in Lemon Butter

Prep Time10 minutes mins

Cook Time10 minutes mins

Total Time20 minutes mins

Course: Main Course

Cuisine: American

Servings: 4 servings

Ingredients

• For the fish
• 4 flounder fillets
• 2 tablespoons melted butter
• 2 tablespoons freshly squeezed lemon juice
• kosher salt and freshly ground white pepper to taste

For serving

• 1 lemon very thinly sliced
• fresh Italian or curly parsley, minced

Instructions

• Rinse and pat dry the fillets. Arrange in on a baking tray.
• Combine the melted butter and lemon juice and drizzle evenly over the fish, reserving about 1 tablespoon.
• Lightly sprinkle with salt and pepper.
• Broil the fish on the highest rack until the fish is white and is just starting to flake, about 5-7 minutes.
• To serve, drizzle on the last tablespoon of lemon butter. Arrange lemon slices on each fillet and sprinkle with the freshly chopped herbs.

Some of My Favorite Ingredients