per 100 grams
Carbohydrates 0 g
Proteins 15.2 g
Fats 2.4 g
Water 81.1 g
Sugar 0 ug
Fiber 0 ug
Starch 0 ug
Trans Fats 0 ug
Cholesterol 0 ug
Ash 1.5 grams


86 Calories per 100g

A flatfish is one of the most remarkable—and, at times, confusing—fish in the ocean. Flatfish, with their two-dimensional shape and eccentric swimming patterns, can be found from the shallow waters of the world’s seas and oceans to the deep, murky depths.

Their strange form and behavior have been a source of fascination for millennia, as far back as ancient Greece, and numerous myths and legends have emerged as a result. But what exactly is a flatfish and how did it come to be?

Anatomy of a Flatfish

Flatfish, also known as pleuronectiforms, have the unique anatomy of being able to lie on the ocean floor. They possess both eyes on the same side of their heads and a flattened, asymmetric bodies. This means that one side of the fish is dark while the other is left colorless. Their particular shape enables them to not just lie on the seabed but also to travel across it.

Most flatfish have large mouths, in proportion to their bodies, that allow them to scoop up prey such as mollusks, crustaceans and fish. They also have an operculum, or hard cover, to protect their gills. The body usually comes equipped with two fins: one dorsal fin near the top, and one lower pectoral fin. With these fins, flatfish are able to swim in any direction, up to about 8 km/h.

Flatfish also possess a detachable jaw, which allows them to swallow their prey whole and keep from being detected by alert predators. Additionally, some flatfish have a getaway strategy when approached by predators, where they remove the fleshy skirt that covers their cheeks and scoot away using their fins.

The Evolution of the Flatfish

Flatfish have captured the attention of scientists since the 19th century, and recent advances in evolutionary biology have allowed us to piece together clues about their origins.

It’s thought that flatfish first evolved in the Early Cretaceous Era, right before the transition to the Late Cretaceous. During this time period, the continents of the world were shifting, with land bridges forming and migrating species passing through them.

We now know that the earliest flatfish to inhabit the seas were bony fish, and that from those bony fish, more advanced species eventually arose. It’s believed that the transition from swimming to crawling on the sea bed occurred in two steps. First, the shape of the bony fish developed so it could lie on the bottom. Then, one of the eyes migrated to the opposite side of the head.

Eventually, the first true flatfish came into existence, with an eye permanently located on the top side of their body. Flatfish have continued to evolve over time, leading to the various species of flatfish we see today.

Behavior of Flatfish

One of the most remarkable features of the flatfish is its unusual behavior. When first born, most flatfish are symmetrical, with both eyes on one side of the head. As they mature, however, one eye migrates to the other side. This shift allows the flatfish to remain hidden in the sand or mud of the ocean floor, with its back camouflaged.

Flatfish are adept at the art of camouflage, often laying perfectly still and blending into their environment. It’s also believed that their eyespots help to make them nearly invisible to predators. However, flatfish also engage in more active forms of defense such as changing their color to match the bottom of ocean.


Flatfish are some of the most fascinating creatures of the sea. With their unique body shape and behavior, they are an evolutionary marvel. From their asymmetrical bodies to their color changing tricks, flatfish demonstrate an impressive level of adaptation in order to survive in the deep ocean. It's no wonder they continue to capture the attention of scientists and spawn myths and legends.