Fluke vs Flounder: All You Need to Know

Mar 12, 2021 | 4 minute read Comments
22
Reading Time: 4 minutes

Flounder is one of America’s favorite inshore fish. It’s fun to catch, delicious to eat, and shows up all along the Atlantic and around the Gulf of Mexico. The only problem is, there’s much more than one species. Fluke vs. Flounder, Summer vs. Winter, Southern vs. Northern – it can be tough to tell which one you’ve hooked.

A close-up of a Flounder fish, focusing on its face.
It’s a Flounder, but which one?

If you’re confused about the nation’s favorite Flatfish, fear not! This article is all about the difference between Fluke and Flounder. You can learn where they live and how to tell them apart. You can also decode the various names these tasty bottom dwellers have picked up over the years.

What’s the Difference Between Fluke and Flounder?

Put simply, Fluke is Flounder. Fluke is another name for Summer Flounder, a large, predatory species of Flatfish that lives in the North Atlantic. The reason people get confused is that Winter Flounder also live in the same place. Luckily, there are some easy ways to tell the two apart.

A diagram explaining how to recognize Fluke vs Flounder. Fluke, or Summer Flounder, is above. Winter Flounder is below. The writing on the left explains that Fluke faces left and Winter Flounder faces right.

Flounder are specially adapted to a life on the bottom. So much so that one eye “migrates” across their head as they get older, until both eyes are on the same side of their face. Fluke are “left-facing,” meaning that when you hold one up, their head will be in your left hand when their eyes are above their mouth. Winter Flounder are the opposite (“right-facing”).

That’s fine when you’re holding the fish, but what if it’s in the water? Easy: Winter Flounder are darker than Summer Flounder. They can look almost black – hence their nickname, “Blackback”. Summer Flounder are light brown with cream or whitish spots. Flounders are able to change color to match their surroundings, though, so their faces are the surest way to tell them apart.

Things get a little more tricky when you come to Southern Flounder. Southern Flounder looks similar to Fluke. It’s the same size and color and it points the same way. So how do you tell them apart? Simple: spots. Summer Flounder have three ringed, eye-like spots near their tail, and several more on their back. Southern Flounder have dark patches instead, as if someone forgot to put the spots on them.

Flounder Distribution

A map showing the distribution of Southern Flounder, Fluke, and Winter Flounder on the US East Coast. Southern Flounder is marked in red, the overlap of Southern Flounder and Fluke is marked in orange, and the overlap of Fluke and Winter Flounder is marked in yellow.

Don’t worry, most of the time you won’t have to worry about telling the difference between Southern and Summer Flounder. The reason for this is that they prefer different waters. With that in mind, here’s a look at where the different Flatfish live. The key is in the name.

Southern Flounder show up along the Gulf of Mexico and up the Atlantic to southern Maryland. Fluke are also known as “Northern Flounder.” You can find them in the Carolinas, but they’re much more common north of the Chesapeake Bay. Winter Flounder live the farthest north, starting in Maryland and going up all the way to Canada.

Fluke vs. Flounder: Summing Up

There are three main species of Flounder on the East Coast. Here’s a brief summary of what makes each one special:

Summer Flounder

A happy angler in a cap standing at the back of a fishing charter boat and holding up two large Summer Flounder, also known as Fluke.
  • Summer Flounder is also known as “Fluke” or “Northern Flounder.”
  • Its head faces left when you hold it up.
  • It ringed, eye-like spots near its tail and on its back.
  • It lives from North Carolina to Maine.

Winter Flounder

A fisherman in orange waterproof trousers and a dark windproof coat holding a Winter Flounder on a boat. There are two fishing rods behind him on the right.
  • Winter Flounder is also known as “Blackback Flounder.”
  • Its head is on the right when you hold it up.
  • It is much darker than other Flounders.
  • It lives from Maryland to Labrador in Canada.

Southern Flounder

A smiling angler in a bikini and a straw hat holding a Southern Flounder on a boat.
  • Southern Flounder is “left-facing” and looks similar to Fluke.
  • It has dark patches instead of ringed, eye-like spots.
  • It prefers warmer waters than most Flounder species.
  • It lives from Maryland to Florida and in the Gulf of Mexico.

These are the main three species, but there are many more Flounders out there. Hopefully, we’ve managed to clear up some of the confusion around these delicious Flatfish. As with so many things in fishing, the best way to learn the rest is to get out there and bag one yourself!

What’s your favorite Flounder? Do you know any other ways of telling them apart? Drop us a line in the comments below, we would love to hear from you!

Comments (22)
  • Michael

    May 28, 2022

    Flounder fishing is big in Argentina’ sea

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      Lisa

      May 30, 2022

      Hi Michael,

      Thank you for your comment. I heard about fly fishing for Flounder along the coast. Do you have any spots you can recommend?

      Lisa

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  • Clemente Bianchi

    May 23, 2022

    What’s a Flounder who’s eye doesn’t migrate & swims upright instead of flat on the bottom like sole?

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      Andriana

      May 24, 2022

      Hi Clemente,

      Thanks for the question, and a good one at that. From what I know, all flatfish have their eyes migrate to one side of their head sooner or later in their life. They also move horizontally, close to the bottom because that’s their preferred way of hunting and feeding, they’re ambush predators. I don’t know of any particular flatfish that fits your description. The closest thing that comes to mind is a Monkfish, though they’re not completely flat, but rather saggy.

      Can you tell me more about where you found the fish you described or how you heard of it? Maybe we can find the mystery fish together.

      All the best!

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  • James McClellen

    Sep 2, 2021

    Do flounders have scales? It doesn’t appear so. Is it hard to remove their skin?

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      Katie

      Sep 3, 2021

      Hi James,

      Thanks for your comment. Great question! Flounder do actually have scales, but they are tiny and very hard to see. Removing their skin is a very simple process. If you’re used to preparing and skinning fish such as Cod or Haddock, you’ll be pleased to know that skinning Flounder is exactly the same. There are step-by-step guides online, but it basically just involves piercing the skin and moving the knife back and forth underneath it.

      Let us know if you have any other questions!

      Tight lines,

      Katie

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      Robert

      Sep 11, 2021

      a very sharp and flexible thin blade fillet knife makes it much easier

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      Lisa

      Sep 14, 2021

      Hi Robert,

      You’re absolutely right! Do you have any recommendations on the knives you use?

      Lisa

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  • Jon Lynch

    Aug 12, 2021

    You left out the most obvious. Look at their mouths! Fluke have big, teeth lined mouths with jaws.
    Winter flounder have tiny mouths with lips.

    Sometimes it’s the most obvious answer. Smh.

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      Karin

      Aug 12, 2021

      Hello Jon,

      We tried to stick with differences that are still visible from a bit further away, but of course, you are absolutely correct!
      Thank you for adding to the topic!

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      Jeff

      Sep 12, 2021

      I had someone tell me yesterday that winter flounder morph into summer flounder. Is that true? I don’t think so but he was adamant that is the case. I tried to point out the differences but he was sure it was a fact that they morph into fluke.

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      Lisa

      Sep 14, 2021

      Hi Jeff,

      Thank you for your comment. I haven’t heard of such a theory before!

      These asymmetrical bottomfeeders are both flatfish. The Winter Flounder, Pseudopleuronectes americanus, have their eyes positioned on the right side of their bodies, while the Summer Flounder, Paralichthys dentatus or Fluke, have their eyes positioned on the left side. Winter Flounder have small teeth, unlike Summer Flounder, whose teeth are huge. There are also, of course, slight color differences. Summer Flounder tend to grow larger than Winter Flounder.

      I haven’t managed to find anything that supports the theory that Winter Flounder morph into Summer Flounder. Has he perhaps told you why he thought they did?

      Looking forward to your answer,

      Lisa

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      james hanna

      Jul 5, 2022

      no way there eyes could migrate from the right to the left. Never heard of something so far fetched

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  • Melissa

    Jul 26, 2021

    I often see American recipes for flue and flounder and as I live in Australia wondering what I would use instead.

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      Vuk

      Jul 26, 2021

      Hi Melissa,

      While they might not be the exact same, you may want to start with a local species like Greenback or Yellow-belly Flounder. The former goes great with verjuice and sorrel, but feel free to try it out with any American recipes you found and liked.

      Be sure to let us know how it went!

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  • Charlotte

    Apr 27, 2021

    This was a great explanation of the differences in looks, but what about the taste? Do the different flounders taste the same?

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      Sean

      Apr 27, 2021

      Hi Charlotte,

      That’s a good question.

      When it comes to taste, Fluke and Flounder are pretty similar. The meat on both is lean and mild tasting, but there’s a difference in texture. While Fluke are smoother and firmer, Flounder tend to be rougher and more flaky. That’s why some restaurants serve Fluke as sashimi. At the end of the day, both fish taste great when fried.

      I hope you’ll find this helpful.

      Bon appétit!

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  • Tara Ferraro

    Oct 14, 2019

    Fluke also have nice sharp teeth! LOL

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  • w biegel

    Jul 17, 2019

    I have always noticed that Flounders have smaller mouths (lips) versus
    Fluke which have a large mouth with an apparent lower jaw.

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      Albert

      Jul 18, 2019

      Hi Biegel,

      You’re definitely right there. (Winter) Flounder seem to have smaller heads in general.

      Any other tips on telling them apart?

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      jeffrey brown

      Jun 21, 2020

      So the summer, light colored, left facing, is a fluke/flounder in which case its he same fish with two names??
      And the darker, right facing is a winter flounder. his is correct??

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      Albert

      Jun 22, 2020

      Hi Jeffrey,

      Yes, Summer Flounder and Fluke are the same thing (the left-facing and lighter species).

      However, when people in the Northeast say “Flounder” they usually mean Winter Flounder, because they generally call Summer Flounder “Fluke.” You may also hear people refer to Winter Flounder as “Blackback” because of its darker color.

      Hope that clears up the confusion!

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