Halibut vs Flounder – Is There A Difference? Let’s Compare

Halibut and flounder are often compared due to their similar flatfish shapes. Although there are various differences leading many people to ask about the two fish. Therefore, let’s answer the question, what is the difference between halibut and flounder?

Halibut and flounder are different species although from the same flounder suborder Pieuronectoidei. Halibut provides a larger percentage of nutrients than flounder. Halibut has a firmer texture and is less flakey than flounder. Halibut costs approximately $17 more per pound than flounder.

This article will compare their tastes, textures, cooking methods, costs, mercury levels and whether one can substitute for the other in recipes. In addition, I’ll do a side-by-side comparison of their nutrients, habitats, size, weight and more.

Halibut and Flounder Nutritional Value

The following table is a side-by-side comparison of all the nutrients in halibut and flounder:

Nutrient Halibut, raw (4 Ounces) Flounder, raw (4 Ounces)
Calories 103 79
Fat 1.5 g 2.2 g
Saturated Fat 0.3 g 0.5 g
Cholesterol 56 mg 51 mg
Protein 21 g 14 g
Omega-3 0.25 g 0.31 g
B-6 0.6 mg 0.1 mg
B-12 1.2 mcg 1.2 mcg
Thiamin 0.05 mg 0.02 mg
Riboflavin 0.03 mg 0.02 mg
B5 0.3 mg 0.4 mg
Niacin 7.3 mg 1.1 mg
Folate 13.6 mcg 5.6 mcg
Iron 0.1 mg 0.2 mg
Potassium 493 mg 181 mg
Magnesium 26 mg 20 mg
Phosphorus 267 mg 285 mg
Calcium 7.9 mg 23.8 mg
Zinc 0.4 mg 0.3 mg
Selenium 51.7 mcg 30.2 mcg

Nutrient sources 1 2

After examining the nutritional table above, it’s easy to see both fish contain many vitamins and minerals. Therefore, which is healthier, halibut or flounder?

Halibut is healthier due to its higher percentage of B vitamins and minerals. Halibut provides more B6, thiamin, riboflavin, niacin, folate, potassium, magnesium, zinc and selenium. Halibut contains more protein and fewer total and saturated fats than flounder.

Flounder also contains a good number of of vitamins and minerals. Flounder provides more omega-3 fatty acids, B5, iron, phosphorus and calcium than halibut.

Both fish contained the same amount of B12. Keep reading and find out why omega-3 fatty acids and the various vitamins and minerals are important to your health.

Halibut and Flounder Health Benefits

Both fish provide the same nutrients and therefore the same benefits. Although I broke down the benefits by which fish offers the higher percentage of each nutrient 3.

Halibut Health Benefits

B Vitamins

The B vitamins provided by halibut and flounder include B1 (thiamin), B2 (riboflavin), B3 (niacin), B9 (folate) B6, B12 and B5. B vitamins help support the following:

  • Energy levels.
  • Red blood cells.
  • Cardiovascular disease.
  • Digestion.
  • Nerve function.
  • Brain function.


There are 493 mg per four ounces of raw halibut. Potassium helps the body get rid of excess sodium which helps reduce fluid build-up. These help keep systolic and diastolic blood pressure lower 4.

The more potassium you consume, the more sodium your body will lose. Consuming too much sodium or not enough potassium throws off the delicate balance the kidneys need to remove the excess water 5.

According to Harvard Health, a number of studies have shown a connection between low potassium levels and increased blood pressure 6.


There are 26 mg of magnesium per four ounces provided by halibut. Magnesium calms and relaxes the whole body including blood vessels. Magnesium has been shown to help improve sleep related problems like insomnia 7.

Magnesium helps keep blood pressure levels balanced and stable. A recent study researched 22 studies and concluded magnesium supplementation decreased diastolic and systolic blood pressure 8.

Magnesium in halibut helps control muscle and nerve function, blood sugar and blood pressure.

In the muscles and heart, magnesium competes with calcium to help the muscles relax after contracting. When the body is low in magnesium, calcium can over stimulate the heart muscle’s cells causing a rapid or irregular heartbeat.


There are 51.7 mcg of selenium per four ounces of halibut. Selenium is a nutrient which doesn’t receive much press. I’m unsure why many don’t write about it more because studies 9 show selenium may help to protect the following:

  • Heart disease
  • Thyroid
  • The immune system
  • Cognitive issues


Also known as B9, halibut provides 13.6 mcg per four ounces. A deficiency in folate has been linked to depression in people with epilepsy. Low folate has been associated with an increased risk of depression 10.

Folic acid (B9) can improve blood flow and help blood vessels to relax. In a study of over 3,000 women, the findings suggest that using folic acid containing supplements may lower the risk for high blood pressure during pregnancy and preeclampsia 11.

Find out how flounder compared to cod in my article, Flounder vs Cod: Is One Better? Let’s Compare.

Flounder Health Benefits

Omega 3 Fatty Acids

Flounder provides 0.31 grams of omega-3 and halibut 0.25 grams per four ounces raw. Omega-3 fatty acids are heart healthy and help keep arteries healthy. The omega-3s in flounder may help with the following:

  • Keeping bad cholesterol low.
  • Keeping good cholesterol high.
  • Reducing inflammation.
  • Reducing plaque build-up.
  • Lowering triglycerides
  • Help keep the heart rhythms more normal.

DHA and EPA, two of the fatty acids, are associated with lowering blood pressure and improving the health of blood vessels 12.

Studies suggest omega-3s can help reduce joint pain and stiffness in people with rheumatoid arthritis. They may also boost the effectiveness of anti-inflammatory drugs.


There are 285 mg of phosphorus per four ounces of raw flounder. It has been shown in scientific research to help with the following:

  • Muscle recovery after exercise.
  • Muscle contraction.
  • Help the body store and manage energy.
  • Help the kidneys remove waste.
  • Promote healthy nerve conduction.
  • Promote teeth and bone strength.


Flounder provides 23.8 mg of calcium per four ounces. Calcium is important for blood pressure and the heart. Harvard Health reports calcium helps maintain blood pressure because it helps to control the relaxing and tightening of blood vessels 13.

Calcium also helps the following:

  • Build and maintain strong bones.
  • Muscles need calcium to function properly.
  • Improve nerve function.

Found out how halibut compared to Mahi Mahi and which one provides more vitamins and minerals in my article, Mahi Mahi vs Halibut: What’s The Difference? Let’s Compare.

Halibut and Flounder: Tastes and Textures

One of the most important things people takes into consideration when choosing a fish is its taste. When comparing the two fish, does halibut and flounder taste the same?

Halibut and flounder both have a similar mild to slightly sweet taste. Neither fish has a fishy flavor. Halibut typically has thicker fillets than flounder. Flounder’s texture is more delicate than the firmer texture of halibut. Flounder is flakier and will separate easier when eating.

What does flounder taste like? Flounder has a mild to slightly sweet flavor. It doesn’t taste oily and has a flaky, delicate texture. Flounder doesn’t not have a fishy flavor.

What does halibut taste like? Halibut has a mild to sweet taste. Halibut is typically a thicker cut of fish and has a firm texture and a little flaky.

Halibut and Flounder Substitutions

When preparing recipes for dinner it’s not always possible to locate the type of fish called for. If you have some halibut, you may ask, can I substitute halibut for flounder?

Halibut can substitute for flounder due to their similar mild to sweet tastes. Flounder’s texture is more delicate and may fall apart easier when cooking. Therefore, when substituting halibut for flounder any cooking method may be utilized. 

Flounder can substitute for halibut due to their similar tastes. Due to flounder’s more delicate texture, when substituting, avoid grilling and instead bake, broil, poach or fry. Other halibut substitutes include the following:

  • Rainbow trout
  • Cod
  • Flounder
  • White Sea bass

The best flounder substitutes are:

  • Porgy
  • Cod
  • Smelt
  • Trout
  • Tilapia

When substituting flounder or halibut always stick to the following:

  • Same size and weight.
  • Stick with similar fillets, whole fillet or cross section.
  • Stick with skinless or skin when the recipe calls for one.
  • Texture is more important for certain cooking methods. Like using a firmer texture when grilling 14.

Check out substitutions and a complete comparison between halibut and salmon in my article, Halibut vs Salmon: Which is Better?

How To Cook Flounder

Flounder has a delicate, thin texture which falls apart easy when using cooking methods like grilling. Therefore, it’s best to sauté, poach, bake or fry. Serve with grilled or steamed vegetables, roasted potatoes or quinoa.

Flavor Pairing

  • Lemon
  • Garlic
  • Olive oil
  • Butter
  • Salt/pepper

How To Cook Halibut

Popular cooking methods for halibut include baking, steaming, broiling, grilling and sautéing. Halibut is low in oil, therefore be careful when cooking because it can dry out or stick to the pan quickly. Halibut partners up with squash, potatoes or grilled asparagus.

Flavor Pairing

  • Lemon juice
  • Basil
  • Pesto

How Much Does Halibut and Flounder Cost

The costs for fish will vary depending on how they’re are caught and where they are sold. When purchasing fish, be sure to check the label to see if it is wild-caught or farm raised. Therefore, which is more expensive, flounder or halibut?

Halibut is more expensive than flounder. The average cost for wild caught flounder is $14.49 per pound while the average cost for wild caught halibut is $33.49 per pound. 

I checked the local Freshdirect online supermarket for the current prices of flounder and halibut.

  • Wild flounder fillet
    • $17.99 per pound
  • Fresh, wild halibut fillet
    • $29.99 per pound

I also checked shoprite supermarket:

  • Fresh wild halibut fillet
    • $36.99 per pound
  • Wild Atlantic flounder fillet
    • $10.99 per pound

Halibut and Flounder Mercury Levels

The EPA and The FDA have issued warnings and suggestions regarding mercury levels in fish and how often they should be consumed 15. This is especially important for young infants, developing children and pregnant women.

They established a list of best fish, good choices and ones to avoid based on their mercury levels. Therefore, does flounder or halibut have more mercury?

Flounder has less mercury than halibut. Flounder is listed on the FDA’s best choices list and halibut on the good choices list regarding mercury levels. Halibut is a larger fish than flounder. Larger fish typically contain more mercury than smaller fish. 

Everyone, especially if you’re pregnant, breast feeding or have a young child, always check with a physician prior to eating new foods or changing your dietary habits.

These mercury warnings can change over time or affect only a particular area or state. For any fish, check with your local EPA and FDA for the current recommendations 16.

Find out about cod’s mercury and how it compared to halibut in my article, Halibut vs Cod: The Differences in Detail.

Halibut vs Flounder: Habitats, Size, Weight, Appearance?

Halibut and flounder are both flat fish. For that reason, many people ask, how can you tell the difference between a flounder and a halibut?

The easiest way to tell the difference between a flounder and a halibut is their body shape, tail fin and size. A halibut body is more elongated than the oval shape of the flounder. The flounder’s tail fin is rounded while the halibut’s tail fin is slightly forked. Halibuts weigh more and grow longer than flounders.

picture of a flounder and halibut for comparison
Flounder and halibut

Scientific Classifications, Families, Species

Flounder is the name used to describe many species distantly related. The following are the better-known flounder species:

  • Atlantic Ocean
    • Gulf flounder (Paralichthys albigutta)
    • Summer flounder (Paralichthys dentatus)
    • Southern flounder (Paralichthys lethostigma)
    • Winter flounder (Pseudopleuronectes americanus)
    • Atlantic Halibut (Hippoglossus hippoglossus)
  • European waters
    • European flounder (Platichthys flesus)
    • Witch flounder (Glyptocephalus cynoglossus)
  • North Pacific Ocean
    • Halibut (Hippoglossus stenolepis)
    • Olive flounder (Paralichthys olivaceus)

Halibut have two species of fish both from the same family and genus.

Pacific halibut:

  • Family: Pieuronectidae
  • Genus: Hippoglossus
  • Species: H. stenolepis

Atlantic halibut:

  • Family: Pieuronectidae
  • Genus: Hippoglossus
  • Species: H. hippoglossus

If you take a close look at the list above you may notice halibut is listed under the flounder species. This may be confusing at first. This raises a common question like, is California halibut a flounder?

California halibut or Hippoglossus stenolepis, is from one of the flounder families. The California halibut is part of the Pieuronectidae family, which is one of many families belonging to the flounder suborder Pieuronectoidei.



  • According to the National Oceanic and Atmospheric Administration, Pacific halibut primarily live in the Central Gulf of Alaska near Kodiak Island. Deep-sea fishing for halibut is a popular sport in Alaska.
  • Atlantic Halibut are native to the temperate and arctic waters of the northern Atlantic Ocean. They can be found in Labrador, Greenland, Iceland, Bay of Biscay and Virginia.


  • The gulf, southern, summer and winter flounders are found in the western Atlantic Ocean.
  • The European and witch flounders are found in European waters.
  • The olive flounder can be found swimming in the North Pacific Ocean.

As a general rule most halibut are found north and more flounder are found south. 


  • The upper part of halibut is dark and varies due to the color changing to blend in with the ocean floor. The change in color helps them avoid detection. The underside is lighter.
  • The color of the flounder depends on the habitat. Flounders are typically brown colored with various red, orange, green and blue markings on the body.


  • Halibut have diamond shaped more elongated bodies than other flat fish. They have large arches in the lateral line over the pectoral fin. Their tails are a crescent shape. Both of their eyes are on the darker, upper side of their body.
  • Flounder has an oval, flattened body with bulging eyes both located on one side of the head.

Size and Weight

  • Then Atlantic Halibut female can grow up to 600 pounds. The males average 25-30 pounds and can weigh up to 100 pounds.
    • A 20″ halibut weighs about 3 pounds.
    • A 36″ halibut weighs about 20 pounds.
    • A 58″ halibut weighs about 100 pounds.

The size of the flounder depends on which species. The average weight for flounders are the following:

  • European flounder: 6.4 pounds
  • Winter flounder: 4.4 pounds
  • Witch flounder: 3 pounds
  • Southern flounder: 11 pounds
  • Olive flounder: Grow up to 20 pounds


  • A halibut can live up to 50 years.
  • A flounder can live up to 20 years.


Flounder consume the following:

  • Zooplankton
  • Small invertebrates
  • Large invertebrates
  • Bluefish
  • Squid
  • Shrimp
  • Crabs

Halibut consume the following:

  • Other fish
  • Cod
  • Haddock
  • Herring
  • Sand eels
  • Pogge
  • Large crustaceans

Species Resources 17 18 19 20 21 22 23 24 25 26 27

Read Next – More Fish vs Fish Articles!

White Perch vs White Bass: Which Is Better?

Spotted Bass vs Smallmouth Bass: What’s The Difference?

Sprats vs Sardines – AreThey Different? Let’s Compare

Rainbow Trout vs Brown Trout – What’s The Difference?

Tuna vs Mahi Mahi – What’s The Difference? Let’s Compare


Article Resources: Foods For Anti-Aging follows strict guidelines to ensure our content is the highest journalistic standard. It's our mission to provide the reader with accurate, honest and unbiased guidance. Our content relies on medical associations, research institutions, government agencies and study resources. Learn more by reading our editorial policy.
  1. Nutrition Value: Fish, raw, Atlantic and Pacific, halibut[]
  2. Nutrition Value: Flounder, raw[]
  3. FDA: Seafood Nutrition Facts[]
  4. American Heart Association: How Potassium Can Help Control High Blood Pressure[]
  5. National Center for Biotechnology Information: The Effect of the Sodium to Potassium Ratio on Hypertension Prevalence: A Propensity Score Matching Approach[]
  6. Harvard Health: Potassium lowers blood pressure[]
  7. National Institutes of Health: Magnesium[]
  8. National Center for Biotechnology Information: Effect of magnesium supplementation on blood pressure: a meta-analysis[]
  9. National Institutes of Health: Selenium[]
  10. National Center for Biotechnology Information: Is Depression Related to Low Folate Levels in People with Epilepsy? An Observational Study and Meta-analysis[]
  11. Women And Birth: Folic acid supplement use and the risk of gestational hypertension and preeclampsia[]
  12. National Center for Biotechnology: Marine Omega-3 Supplementation and Cardiovascular Disease[]
  13. Harvard Health: Key minerals to help control blood pressure[]
  14. Sea Grant North Carolina: Fish Flavors and Substitutions[]
  15. FDA: Advice about Eating Fish[]
  16. National Center for Biotechnology Information: Mercury accumulation in largemouth bass (Micropterus salmoides) in a Florida lake[]
  17. NOAA Fisheries: Summer Flounder[]
  18. NOAA Fisheries: Winter Flounder[]
  19. NOAA Fisheries: Yellowtail Flounder[]
  20. NOAA Fisheries: Witch Flounder[]
  21. NOAA Fisheries: Windowpane Flounder[]
  22. NOAA Fisheries: Arrowtooth Flounder[]
  23. NOAA: Pacific Halibut[]
  24. University of Maine: Maine Seafood Guide – Halibut[]
  25. Wikipedia: Pacific halibut[]
  26. Wikipedia: Atlantic Halibut[]
  27. Wikipedia: Halibut[]

Kevin Garce

Kevin Garce is a Certified Health Coach who encourages people by informing them on nutrition and food topics important to them. His years of research and knowledge inspire people to achieve their goals. Read more here About Me

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