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flounder summary

Flounder are a group of saltwater flounder native to South America. Their odd-shaped bodies are completely flattened, with both eyes located in the upper half of the body.

They are demersal fish, which means they exist on the bottom of oceans or in estuaries, where they camouflage themselves and lean against the substrate. This fish belongs to a unique group of fish with a typical flat body.

3 Unusual Facts About Flounder

  1. Flounders are born with eyes on both sides of their bodies, but they don't last long. The other eye will soon move to the top of their body.
  2. Females are slightly larger than males, reaching lengths of up to 37 inches in some species.
  3. Flounders appear normal at birth and undergo a metamorphosis, becoming a flounder with the eyes moved to the top of the body.

Flounder species

Flounders are a group of distantly related several different species. They are classified in the same suborder Pleuronectoidei in a different family. These families are divided into right- and left-eye families, and the most common are European flounder, summer flounder, and dusky flounder.

European waters:

  • European flounder (platichtyhys flesus)
  • Witch Flounder (Glyptocephalus cynoglossus)

western atlantic

  • Halibut (paralichthys dentatus)
  • Winter flounder (pseudopleuronectes americanus)
  • Gulf Flounder (Paralichthys abigutta)
  • Southern flounder (paralichthys lethostigma)

North Pacific Ocean

  • Olive flounder (paralichthys olivaceus)
  • Flounder (hippoglossus stenolepis)

flounder appearance

Flounders start life with their eyes on either side of the head, but as they mature their eyes migrate to the top of the body
Flounders start off with eyes on the sides of their heads, but as they mature, their eyes migrate to the top of the body!


Flounders have an interesting appearance because they are benthic, or in other words, feed on or near the ocean floor or the bottom of lakes, flounder species. Their appearance varies from species to species, but adults of all species are 8 to 37 inches (20-94 cm) long and only half their length wide. The bodies are characterized by being flattened so that they can blend into the seafloor as a form of camouflage.

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The flattened body of the flounder is the result of metamorphosis. In the larval stage, they appear to be normal fish. As adults, their bodies become completely flat! Juvenile flounder are born with eyes on both sides of the head, but when they reach the larval stage, one of the eyes migrates to the top of the body. Their flat appearance is well suited to their benthic behavior.

Depending on the species, they can weigh up to 22 pounds. The hard scales act as camouflage on the sea floor, and some can even change their body color! They can be orange, green, white, or tan in color.

Flounder Distribution, Populations and Habitat


Flounder is native to South America and lives mainly in the Pacific and Atlantic Oceans. However, some live in other regions and around the world, such as the Atlantic coast of North America, the North Pacific Ocean, and the coasts of Europe.


The two families of flounder (Paralichthyidae and Bothidae) contain about 240 species, and the family Plueronectidae accounts for about 100 species of flounder. A wide variety of species inhabits Aral Seas around the world. They live along shorelines, where they lie flat on the substrate.

The conservation status of most species is stable, but the Atlantic flounder is considered endangered according to the IUCN list.


Flounder is a bottom-dwelling fish. Most live in salt water, but some prefer fresh water. The few species that live in freshwater environments require higher salinity, called brackish water, and inhabit freshwater basins, lakes and rivers.

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They live in shallow waters of temperate and tropical oceans, such as near coastlines, but a few species live in deeper waters. They spend most of their time lying flat on the bottom of the sea, and they are ambush predators.

Flounder predator and prey

Flounders fall prey to humans, eels, large fish and sharks. They are well camouflaged and difficult to spot, making them less likely to be caught by predators. Some species are considered prey, and overfishing by humans has reduced their numbers.

These ambush predators line the ocean floor waiting for prey to swim or crawl near them so they can quickly catch them. Their prey includes small fish, crustaceans, fish eggs, and polychaetes.

Flounder Reproduction and Lifespan

Baby flounder are born with eyes on both sides of their body, but as the fish grows, one eye moves.
Flounder fry start out with eyes on both sides of their body, but as the fish grows, one eye moves.

©Gaurav Ruke/Shutterstock.com

Reproductive strategies vary by species, but all reproduce by laying eggs. Reproduction occurs outside the body, with the female releasing her eggs into the water and the male fertilizing the eggs. Some species reproduce in large numbers, while others lay fewer eggs.

The average lifespan is between 8 and 11 years. Females mature faster at 1 year, while males take longer.

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These demersal fish are found on the bottom of oceans around the world, while some species are also found in estuaries. Flounder is native to South America, but species such as summer flounder can be found in offshore and offshore waters from Canada and Nova Scotia to the east coast of Florida.

Flatfish are ambush predators, and their diet includes fish eggs, small fish, crustaceans, and polychaetes. They lie on the ocean floor, waiting for unsuspecting prey.

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Flounders have an unusual way of swimming in that they swim on their sides. They swim using their powerful caudal fins and not their pectoral fins. Plaice like to lie on the substrate and barely swim around.