Types of Flatfish: the Complete Guide

Mar 12, 2021 | 7 minute read Comments
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Reading Time: 7 minutes

It’s easy to get confused by the different types of Flatfish. They all look similar. They all taste great. What’s more, one man’s Sole is another man’s Flounder, and the names of Flatfish are often different in the ocean and on your plate. With that in mind, we’re diving into the muddy waters of these piscine pancakes to cut through the jargon and explain what’s what.

A close-up of a Flatfish face, showing two eyes on one side of its head.

Flatfish are a common catch in both the US and the UK. Some are the same in both countries, but many of them aren’t. This article will give you a basic rundown of the most popular Flatfish in North America and in Britain. You can also learn a little about how the family fits together – what makes a “flat fish” a Flatfish, so to speak.

What’s a Flatfish: a Quick Overview

“Flatfish” is a catch-all name for more than 700 different species of fish. The group includes Flounder, Halibut, Sole, Plaice, Dab, Turbot, and more. It’s important to note that half the time these names don’t follow any kind of scientific classification. Pretty much all our favorite Flatfish are technically Flounder, but most of them go by another name.

Flatfish spend their lives lying on the seafloor waiting for a meal to swim their way. Because of this, they’re perfectly designed for a life on the bottom. Their dabbled skin changes color to match their surroundings and their white underside makes them invisible from below if they ever leave their muddy home.

Two Flatfish camoflaged in white sand on the ocean floor.

To top it all off, their whole head is twisted sideways. Flatfish start out round, but as they grow, their body starts to flatten out. One eye “migrates” across their head and their mouth twists to the side. The group is divided into “right-eye” or “left-eye” fish depending on which eye moves. If you hold one up and it faces right when its eyes are above its mouth, it’s right-eyed. Either way, it’s not pretty.

This brings us on to a very important point: Just because a fish is flat, that doesn’t automatically make it a Flatfish. The group doesn’t include Rays, Skates, Monkfish, or other squashed-looking species. It only refers to the wide family of fish with two eyes on one side of their face.

Types of Flatfish in North America

Now that you know the basics, it’s time to tackle the specific species you can find in North America. If you’re only interested in British waters, feel free to skip down to the next section. Reading both parts will give you the clearest picture of how the family fits together, though.

Flounder

A Summer Flounder, also known as Fluke, lying on a rubber mat on the floor of a fishing charter boat. It has a bright green and red lure in its mouth and another bright green lure by its tail.

In essence, Flounder is the general name for hundreds of different fish. The group includes Halibut, Plaice, Dab – pretty much every Flatfish in North America. To keep things simple, let’s stick to the fish that actually have Flounder in their name.

Most North American Flounders live along the Atlantic and Gulf Coasts. The most popular ones are Summer Flounder (Fluke), Winter Flounder (American Lemon Sole), and Southern Flounder. We’ve covered these three in more detail here. On the West Coast, you also have Starry Flounder and California Flounder. More on that below.

Halibut

A happy angler in orange overalls and a cap holding up a Pacific Halibut on a fishing charter. There is another angler in yellow to the right of the photo and two fishing rods on the left.

Halibut are the undisputed kings of the bottom, reaching over 8 feet long and several hundred pounds in weight. The two species of “true” Halibut are Atlantic and Pacific Halibut. Sadly, Atlantic Halibut is now endangered, so most of the fish for sale in North America is Pacific Halibut caught in Alaska.

Simple so far? Keep reading. California Flounder is often called “Halibut” because it’s a similar shape. There’s also Greenland “Halibut,” which the FDA rebranded to Greenland Turbot to avoid confusion. The fact that it’s not a Turbot either didn’t seem to matter. If you want specifics on the difference between Halibut and Flounder, we’ve gone into more detail here.

Sole

Image source: Linda Snook/MBNMS, Wikimedia

American Sole is a family of fish with small, barely noticeable heads and their high tolerance for fresh water. They’re a different family to European Soles, although the most popular ones are named after species in Britain. On the Pacific Coast, they include English, Petrale, Curlfin, and Pacific Dover Sole (not the same as European Dover Sole).

There are also a couple of fish on the East Coast that people call “Sole,” namely Winter Flounder (“Lemon Sole,” but a different species to European Lemon Sole), and Witch Flounder (which sometimes goes by “Grey Sole”). If you’re buying Sole in a shop or a fish market, it’s most likely Pacific Dover Sole or American Lemon Sole, depending on where you live.

Plaice

An American Plaice fish on a blue background
Image source: NOAA NEFSC Photo Gallery

Plaice is a name given to four different species of right-eye Flounder. Two of them live in North America, the most common of which is American Plaice. This fish lives on both sides of the Atlantic, and goes by the name “Rough Dab” in Europe. There’s also a species in the Pacific called Alaska Plaice.

North America’s biggest commercial Plaice fishery is in Labrador in Canada. Chances are that any Plaice you buy was caught there. Alaska Plaice aren’t a huge target commercially and you won’t normally find them for sale unless you live on the North Pacific coast.

And So Much More!

There are a dozen more Flatfish names in North America. In short, they’re all Flounder. If you see something sold as “Turbot,” it’s either Greenland Halibut, Arrowtooth Flounder, or Curlfin Sole. Just bought some “Brill?” It’s probably Petrale Sole. All of these are Flounders.

Types of Flatfish in the UK

Flatfish are a lot less confusing in the UK. For one thing, there are far fewer species than in North America. There’s also the fact that they weren’t named at random by European settlers based on what they vaguely looked like. Here are the most common species.

Flounder

A European Flounder swimming underwater with gravel beneath it
Image source: Tiit Hunt, Wikimedia, (CC BY-SA 3.0)

There’s only one fish in the UK called Flounder – European Flounder. These guys live all around the Britsh Isles and are a regular target for anglers and commercial crews alike. Despite this, Flounder stocks are much healthier than other British Flatfish, making it a good alternative if you’re looking for sustainable fish.

You can recognize Flounder by their long body and wide dorsal fins which give them a diamond shape when they’re extended but fold flat against their sides. Despite this, Flounder often gets mixed up with European Plaice. If you can’t tell which one you’re looking at, check the head. Plaice have a bony ridge on their heads, Flounder don’t.

Plaice

A smiling angler holding a large European Plaice with sea behind him
Image source: Hans Ngf, Flikr (CC BY-ND 2.0)

Speaking of Plaice, these are one of the most popular Flatfish to eat in the UK. As well as the commercial harvest, they’re a favorite among British sea anglers. The easiest way to identify Plaice is by their signature orange spots. They also have rounded dorsal fins, and have a clearly defined head like Flounder.

Similar to Flounder, European Plaice stocks seem to be healthy at the moment. They were massively overfished in the 1970s and ‘80s, but their numbers are now increasing, according to the International Union for the Conservation of Nature.

Turbot

A Turbot, one of the most expensive types of Flatfish in the world, lying on the floor of a boat.

Turbot are the tastiest and most expensive type of Flatfish. So much so, that they have earned the nickname “King of Fish.” This makes Turbot a favorite for both commercial and recreational fishers. It also means that you sometimes find other fish sold as Turbot in less reputable restaurants.

Of course, there’s another downside to Turbot being so tasty: overfishing. Turbot numbers are decreasing and the species as a whole is vulnerable to extinction, according to the IUNC. If you want our advice, stick to other Flatfish species that cost half as much and aren’t nearly as overfished.

Sole

A Devon Sole, one of the most popular types of flatfish in the UK, laid on a stone slab

There are two species of Sole in the UK: Dover Sole and Lemon Sole. Neither of them are the same as their American counterparts, and some British anglers even see American Soles as fakes of their favorite foods. Dover Sole gets its name from the southern port town of Dover, and it’s most common in the South of England, but both these fish show up all around Britain.

Sole are easy to recognize, thanks to their long body and small head. Dover Sole is a much more important fish, both commercially and recreationally. It lives in much shallower water, so it’s easier to get to. On top of that, Lemon Sole have a tiny mouths that make them difficult to hook even if a sea angler comes across one.

And More!

Chips shops and fishmongers around the country are full of different Flatfish. Some, like Dab, have become common on British menus since more prestigious fish grew scarce. Others, like Brill, have always been enjoyed, but have never been as popular as mainstay species like Plaice or Sole.

And of course, there are some species, like Atlantic Halibut, which you can still buy but which are tragically endangered in the wild. If it has to be Halibut, make sure it’s Alaskan Halibut, as these guys are much more sustainably managed.

Summing Up: the Many Names and Types of Flatfish.

A Summer Flounder, one of the most common types of Flatfish in the US, poking its eyes out of the water in a shallow pool.

If there’s one thing you can take away from all this, it’s that the names of Flatfish often have very little to do with the species themselves. Dozens of fish go by a handful of names, and most of them are called something different elsewhere.

Whatever you call them, all Flatfish have a few things in common. They live on the bottom, their faces are the stuff of nightmares, and they taste absolutely delicious. Oh, and if you’re not sure what you’ve caught, chances are it’s technically a Flounder.

What are your favorite types of Flatfish? Do you catch any of them regularly? Did we help you make sense of the many confusing names these bottom-dwellers have? Let us know in the comments below, we love to hear from you!

Comments (30)
  • Frank Gruber

    Jan 25, 2022

    Thank you for the interesting article . In 1973 I got a job at a small- fish processing company in North Myrtle Beach SC. I learned how to Filet a flounder there and they referred to it as a “Rough Back”.
    Have you ever heard of it described like that ? I don’t think it was from local waters because all the boats going out were going for Sea Bass and never flounder that I remember.
    Thanks

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      Andrijana Maletic

      Jan 26, 2022

      Hello Frank,

      Thanks for reading, I’m glad you like the article. Out of all the names we’ve heard for Flounder, “Rough Back” is a new one! There definitely is Flounder in South Carolina, but that’s the so-called Southern Flounder.

      There is a species of Flounder called Rough Scaled Flounder, but these fellas live in the Western Pacific and the South China Sea. So it’s fascinating that they’ve got a similar name for this Flattie all the way on the other side of the world, in South Carolina.

      Thanks for sharing this interesting tidbit with us, Frank.

      All the best!

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  • Doug

    Dec 26, 2021

    Alex, thank you for this informative blog which simplifies things (okay, dumbs them down) in ways a novice like myself can comprehend.

    My question is, how do Sand Dabs rank in the hierarchy of flatfish in terms of dining appeal? I see them on restaurant menus but have never selected them as I default to something I am more familiar with like Halibut or Sea Bass.

    Much appreciated!

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      Lisa

      Dec 28, 2021

      Hi Doug,

      Lisa here. Thank you for reaching out and posting this interesting question! Sand Dabs are much smaller fish, although I can hardly say they are less healthy. They taste similar to Halibut (in my opinion) but the difference here is that they are much, much smaller. Hence, less meat, so you’d normally deep-fry them.

      I hope this helps!

      Lisa

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      john

      Jan 6, 2022

      dabs are great to eat, fry whole in butter, eat with salt n vinegar, bread and butter, so much better than bass

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  • ROBERT WHITE

    Oct 21, 2021

    what a delightfully-written discussion. Sarcastic, yet light-hearted; just a fun read.

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      Lisa

      Oct 21, 2021

      Hi Robert,

      Thank you for reading and taking the time to comment! We’re glad you enjoyed it.

      All the best,

      Lisa

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  • Lee

    Sep 17, 2021

    Isn’t it odd that some of the tastiest fish are funny-looking fish?

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      Lisa

      Sep 20, 2021

      Hi Lee,

      I’ve noticed that, too. Very odd!

      Lisa

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  • Siobhan

    Jul 23, 2021

    Really enjoyed this article. I live in the Canadian eastern Arctic where “Turbot” (possibly Greenland Halibut?) is an important part of the local economy in one of the Baffin communities.

    I was actually looking for an explanation as to why some species developed as predominantly ‘left-eyed’ while others are ‘right-eyed’ but I really appreciate all the other information – very interesting!

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      Katie

      Jul 23, 2021

      Hi Siobhan,

      Thanks for your comment! We’re really glad you enjoyed this article. As for your question about why some species of Flatfish are right-eyed and others are left-eyed, it seems like no one has quite cracked the code to this mystery just yet. However, in 2009, researchers started looking into this topic and hypothesized that it has something to do with certain internal asymmetries that develop in the embryo and genes in the brain, especially one known as pitx2. You can read more here if you’re interested!

      Tight lines,

      Katie

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  • Loren

    Jul 9, 2021

    question,i live on west coast of B.C.i’m fishing in a 100ft plus water,how do i tell difference between small halibut and a big sole

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      Andriana

      Jul 12, 2021

      Hi Loren,

      Thanks for reading, good question!

      The main difference between Halibut and Sole is usually the shape of their body – Halibut are more diamond-shaped, while Sole have more rounded bodies and their eyes are always on the right side of their head. Also, you can tell the difference by looking at the fish’s lower fin – Halibut’s got shorter, more angular lower fin, and Sole has fins running from the tail to the head.

      I hope this helps Loren.

      All the best!

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  • Falaya

    May 28, 2021

    I think this post proved that your are my best friend
    Only this post proved that any body is not equal you and your level

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      Andriana

      May 28, 2021

      Hey Falaya,

      I’m glad you enjoyed the article and thank you for the kind words.

      All the best!

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  • Danilú Couoh

    May 27, 2021

    Hi, is very interisting infortmation, I have a question. How many time can live the flatfishes? How is their live cicle??. I wait for your answer.

    Regards

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      Andriana

      May 27, 2021

      Hello Danilú,

      Thanks for reading. Different Flatfish have different lifespans, so it really depends. Flounder, for example, can live for 20 years, while Halibut and PLaice can live even longer, up to 30 years. The most long-lived Flatfish of them all is Sole – they can live as long as 40 years.

      I hope this helps, Danilú.

      All the best!

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  • Susannah

    Dec 2, 2020

    Hi Albert – strange request – would you be able to ID a “fish” for me? It’s actually a piece of Royal Copenhagen porcelain illustrated in a book I am editing. The author captioned it as “Plaice” but it looks like the wrong shape to me.
    (I can’t seem to post a pic in this comment but can send it to you by email)
    Thanks for your help

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      Albert

      Dec 2, 2020

      Hi Susannah,

      Wow, that’s a new one! Sure, I’d be happy to help if I can. Am I ok to email you at the address you added with your comment?

      All the best!

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      Susannah

      Jan 4, 2021

      Hi Albert,
      Happy New Year!
      Sorry – only just seen your comment.
      Yes, please do e-mail me.
      Thanks

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      Albert

      Jan 4, 2021

      Hi Susannah,

      I’ve dropped you an email. Looking forward to seeing if we can wrap up this Flatfish mystery!

      All the best!

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      James Arthur Lupton

      Sep 14, 2021

      It would be great if you post an image and let us know the answer. I’m really intrigued. I came here because I’m translating an article on the ecology of the flounder Citharichthys gilberti (the Bigmouth sanddab apparently!) in Buenaventura Bay, Colombia…

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      Albert

      Sep 15, 2021

      Hi James,

      I don’t quite understand your question. What would you like an answer on, the small Flatfish served in restaurants?

      Sounds like a pretty technical topic to translate!

      All the best!

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      SALLY GREEN

      Dec 6, 2021

      Hi,James

      I would love to see that picture

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  • Lloyd Eastlack

    Nov 16, 2020

    Many in NC & other southern states ask about the baby flounder served in restaurants. All these states have a size limit which is much larger than what they’re serving. I understand these small fish are sole found and trawl netted in Canadian and Newfoundland waters, they never grow much larger than what is on the plate, but, they are still in the flounder or flatfish family. Thanks.

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      Albert

      Nov 17, 2020

      Hi Lloyd,

      What did you want to know about them? As you say, there are a lot of species of Flounder, some of which are just much smaller. On top of that, the commercial size limit is sometimes different to the recreational one (although I’m not an expert on commercial regulations).

      All the best!

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  • Rich Zaleski

    Nov 3, 2020

    Trying to identify a small flatfish I caught last summer in Long Island Sound It’s shape is much wider than either the fluke (summer flounder) or flatfish (winter flounder) that I’ve caught in northeastern US waters all my life. Almost circular, but with a very sharp “nose”. Left-eyed. Fins were quite translucent, as was the body itself around the edges. A small fish — I would assume a young of whatever species it might be. Unfortunately, it did not pose well for a picture, and kept curling itself up. Didn’t want to keep it out of the water, so I only tried a few shots, and this is the best of them.. fish was actually snagged in the nose taking a whack at a much too large for its mouth, heavy jigging spoon, in 30 feet of water.
    Fishing partner clled it a sand-dab, but I thought those were limited to the pacific coast.

    http://www.richz.com/misc_images/littleflatty.jpg

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      Albert

      Nov 4, 2020

      Hi Rich,

      Looks to me like a Windowpane Flounder, which some people do also call Sand Dabs. The loose fin rays near the mouth are a dead giveaway.

      Windowpanes don’t tend to get that big, and this guy actually looks like a decent catch. Even so, you can’t really get a proper fillet of them, so it’s good that you put it back.

      I hope that helps. Be sure to send any other confusing fish our way!

      Tight lines!

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  • Alex

    Oct 22, 2020

    Here for the explanation on which flatfish was delicious. Aptly put and entertaining explanation. Understand em in a jiff.

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      Albert

      Oct 23, 2020

      Hi Alex,

      Thanks for getting in touch. I’m glad you enjoyed the article.

      Eating flatfish is much simpler than identifying them. They all taste delicious!

      All the best!

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