Difference between Halibut and Flounder
By Theydiffer - July 17, 2016

Whether you’re into game fishing or cooking, knowing the difference between a halibut and a flounder can help avoid embarrassing situations – imagine filleting a flounder, or posting on Facebook that you caught a halibut, when in fact you are referring to the opposite fish. Keep on reading below to steer clear of faux pas only amateurs make.


A flowery flounder

One of several groups of flatfish, flounders also live at the bottom of oceans all over the world. Surprisingly, flounder is a general term for flatfish. By definition, this makes the halibut a flounder.

A fully-grown flounder has its two eyes located on one side of its head. However, when hatchling, its eyes are situated on each side of the brain. Metamorphosis during a flounder’s growth cycle causes one of its eyes to migrate to the top side of its body. Eye migration is common among flounders, and the area where the eye migrates to varies from species to species.

Relative to the type of species, the lateral line on a flounder can be straight, as with that of the winter flounder and the witch flounder, or strongly curved as with that of the left-eyed windowpane flounder and the yellow tail.

Halibut vs Flounder

So, what is the difference between a halibut and a flounder? What do you need to look out for so you can tell the difference right on the spot?

We can always tell things apart by physical appearances, and these flatfish are no exception. Halibut can grow to enormous sizes. In 2013, a Pacific halibut (the largest of the species) measuring 8.6 feet and weighing 515 pounds is known to have been caught in Norway. Flounder, on the other hand, are a lot smaller and typically grow to up to 37 inches.

The halibut has cone shaped teeth concealed within its large mouth. Its scales are less noticeable as its smooth skin easily obscures them. A flounder’s scales are thicker, and its teeth protrude slightly from its diminutive mouth.

The majority of halibut lie flat on the seafloor on their left sides. The color of a halibut’s top side is usually dark brown or mottled green in color, its soft underbelly remains white for the duration its life. The flounder’s eyes may migrate to either side, but they are usually right sided.

Spending most of its time near the bottom of the ocean, the halibut may swim up to feed. The flounder spends the entirety of it life camouflaged on the ocean floor feeding on fish spawn, smaller fish and crustaceans.

Comparison chart

Large mouth with cone-shaped teethProminent teeth and small mouth
Largest halibut ever caught on record weighed 482 lbs (218.6 kg)Summer flounder can weigh up to 26 lbs (11.8 kg)
Lives near the bottom, but may swim up to feedLives on the ocean floor
Eyes are on the right sideLocation of eyes dependent on species