Flounder Fish

Last updated: October 22, 2022
Verified by: AZ Animals Staff
© Becky Gill/Shutterstock.com

There are around 240 different species of Flounder fish

Flounder Fish Scientific Classification

Kingdom
Animalia
Phylum
Chordata
Order
Pleuronechthyidae
Family
Paralichthyidae
Genus
Paralichthys

Read our Complete Guide to Classification of Animals.

Flounder Fish Conservation Status

Flounder Fish Locations

Flounder Fish Locations

Flounder Fish Facts

Prey
Crustaceans, small fish, fish spawn, and polychaetes
Name Of Young
Larval
Group Behavior
  • Solitary/Group
Fun Fact
There are around 240 different species of Flounder fish
Biggest Threat
Overfishing
Other Name(s)
Fluke fish
Predators
Sharks, eels, bigger fish, and humans
Diet
Carnivore
Lifestyle
  • Nocturnal
Type
Demersal flatfish
Origin
South America
Number Of Species
240

Flounder Fish Physical Characteristics

Color
  • Grey
  • White
  • Tan
  • Green
  • Light Grey
  • Dark Grey
  • Sandy
  • Olive-Grey
  • Grey-Brown
  • Light-Brown
Skin Type
Scales
Lifespan
15 - 18 years
Weight
6 lbs
Length
2 to 3 feet
Age of Sexual Maturity
1 -3 years
Venomous
No

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Flounder Fish Summary

Flounder fish are a group of saltwater flatfish species that are native to South America. Their oddly shaped bodies are entirely flat, and both of their eyes are located on the top part of their bodies.

They are demersal fish, which means that they are found at the bottom of oceans or estuaries where they camouflage themselves and lay against the substrate. This fish is in a unique group of fish that have characteristically flat bodies.

3 Unusual Facts About Flounder Fish

  1. Flounder fish are born with eyes on either side of their body, but it does not stay that way for long. The opposite eye will soon migrate to the tops of their bodies.
  2. Females are slightly larger than males, and some species can reach up to 37 inches in length.
  3. Flounder fish appear normal at birth and undergo a type of metamorphosis to a flatfish with eye migration to the top of their bodies.

Flounder Fish Species

Flounder fish is a group of several different species that are distantly related. They are categorized into the same suborder Pleuronectoidei with different families. The families are separated into the right-eyed and left-eyed families, and the European, Summer, and Dusky Flounder fish are the most common.

European waters:

  • European flounder (platichtyhys flesus)
  • Witch flounder (glyptocephalus cynoglossus)

Western Atlantic

  • Summer flounder (paralichthys dentatus)
  • Winter flounder (pseudopleuronectes americanus)
  • Gulf flounder (paralichthys abigutta)
  • Southern flounder (paralichthys lethostigma)

North Pacific

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

Flounder Fish Appearance

Flounder fish start life with eyes on either side of their heads, but as they mature, their eyes migrate to the tops of their bodies!
Flounder fish start life with eyes on either side of their heads, but as they mature, their eyes migrate to the tops of their bodies!

©IrinaK/Shutterstock.com

The Flounder fish has an interesting appearance since they are demersal, or in other words, feeding on or near the bottom of seas or lakes, flatfish species. Their appearance of will vary according to the species, but all species grow to an adult length of 8 to 37 inches (20-94 cm) and their width is only half of their length. The bodies are characteristically flat so that they can blend into the ocean floor as a form of camouflage.

The Flounder fish’s flat bodies are a result of metamorphosis. In the larval phase, they appear to be normal fish. When maturing into an adult, their body becomes entirely flat! Larval flounder fish are born with eyes on either side of their head, but as they reach the juvenile stage one of the eyes migrates to the top of their body. Their flat appearance is ideal for their bottom-dwelling behavior.

Depending on the species, they can weigh up to 22 pounds. The hard scales serve as camouflage against the ocean floor and some can even change their body color! Their colors can range from orange, green, white, or tan.

Flounder Fish Distribution, Population, and Habitat

Distribution

Flounder fish are native to South America, and they mainly live in the Pacific and Atlantic Oceans. However, some live in other regions as well throughout the world, such as the Atlantic coast of North America, the northern Pacific Ocean, and the coasts of Europe.

Population

The two Flounder fish families (Paralichthyidae and Bothidae) contain around 240 species and the Plueronectidae family makes up around 100 of the Flounder species. Various species inhabit salty oceans around the world. They live along coastlines where they lay flat against the substrate.

Most species have stable conservation status, but the Atlantic Halibut is considered to be an endangered species according to the IUCN list.

Habitat

Flounder fish are a bottom-dwelling species of fish. Most live in saltwater, but some prefer freshwater. The few species that live in freshwater environments require a higher salinity content known as brackish waters and inhabit freshwater basins, lakes, and rivers.

They live in the shallow areas of both temperate and tropical oceans such as near the coastlines though a few species live in deeper waters. They spend most of their time flat on the ocean floor along the substrate where they are ambush predators.

Flounder Fish Predators and Prey

Flounder fish fall prey to humans, eels, bigger fish, and sharks. They has such good camouflage that they are difficult to spot which makes them less likely to be caught by predators. Some species are considered game fish and overfishing from humans has caused a decrease in their population.

These ambush predators wait along the ocean floor for prey to swim or crawl near them so that they can quickly catch them. Their prey consists of smaller fish, crustaceans, fish spawn, and polychaetes.

Flounder Fish Reproduction and Lifespan

Baby Flounder Fish start life with eyes on either side of their bodies, but one eye migrates as the fish becomes an adult.
Flounder fry start life with eyes on either side of their bodies, but one eye migrates as the fish becomes an adult.

The reproduction strategies vary according to their species, but they all reproduce from spawning. Reproduction takes place outside of the body where the female releases her eggs into the water and the male fertilizes the eggs. Some species of reproduce in large numbers, while others have smaller spawns.

The average lifespan is between 8 to 11 years. The female matures faster at 1 year, whereas males take longer.

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About the Author

I am a big animal lover that not only enjoys owning and getting to care for them, but also to write about them! I own many fish, along with shrimp, hamsters and a docile tarantula. Writing has become my passion and I am grateful to be able to write about the animals I love so dearly so that I can share my knowledge and expertise in the articles I write.

Flounder Fish FAQs (Frequently Asked Questions) 

Where are Flounder fish found?

These demersal fish are found at the bottom of the ocean around the world, while some species have also been found in estuaries. Flounder fish are native to South America, but species such as the summer Flounder can be found in both offshore and inshore waters from Canada, Nova Scotia, to the east coast of Florida.

What do Flounder fish eat?

Flounder fish are ambush predators, and their diet consists of fish spawns, small fish, crustaceans, and polychaetes. They lie along the bottom of the ocean floor and wait for their unsuspecting prey.

How do Flounder fish swim?

The Flounder fish has an unusual way of swimming, and they lay on their side to swim. They use their powerful tail fin to swim and do not use their pectoral fins. Flounder fish prefer to lay on the substrate and hardly swim around.

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Sources
  1. Wikipedia, Available here: https://en.wikipedia.org/wiki/Flounder#:~:text=Flounders%20are%20a%20group%20of%20flatfish%20species.%20They,world%3B%20some%20species%20will%20also%20enter%20estuaries%20.
  2. Fish Base, Available here: https://www.fishbase.se/ComNames/CommonNameSearchList.php
  3. American oceans, Available here: https://www.americanoceans.org/species/southern-flounder/#:~:text=The%20Southern%20Flounder%20is%20a%20flatfish%20that%20lays,lying%20in%20wait%20until%20their%20prey%20comes%20close.

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