American Oceans

Summer Flounder

The Summer Flounder- also known as Paralichthys dentatus – is a fish common to the Atlantic coast. Other names for the Summer Flounder are Fluke, Northern Fluke, or Hirame, and many love this fish for its iconic form and delicious taste.

Summer Flounder- also known as Paralichthys dentatus

It’s common to find the Summer Flounder both on the dinner table and in saltwater aquariums worldwide.

We’ve got you covered if you’ve been curious to learn more about the Summer Flounder. Read on for a quick guide on the habitat and characteristics of everyone’s favorite flatfish.

Characteristics & Appearance

Summer Flounder have a striking appearance that makes them easy to spot compared to other fish. Here’s some quick info on the physical appearance of the Summer Flounder.

Weight & Length

Summer Flounder grow quickly. Males can grow to more than two feet in length and females up to three feet. Their weight ranges from one to three pounds but can grow as large as 25 pounds or more.

Physical Characteristics & Color

Summer Flounder have a characteristic flat shape that makes them easy to distinguish. Because of this, one can often find them lying flat on the seafloor or their chosen habitat.

The form also makes it so that these fish are “left-eyed flatfish,” meaning that both of their eyes are on the left side of their bodies.

Called the “chameleons of the sea,” Summer Flounder can change their color to blend in with their environment. They can even change to suit different textures for excellent oceanic camouflage.

Their natural color is a dark brown that borders on black from the top. From below, these fish have a white below, which they conceal when they lie down for better camouflage.

The Summer Flounder also has spots across its back that help to distinguish it. There are usually at least five on each fish arranged in a loose X formation.

Lifespan & Reproduction

Summer Flounder have a relatively short natural lifespan, living about 12 to 14 years, though some may live longer.

These fish become capable of reproduction when they’re a few years old and spawn multiple times throughout their lives.

After an offshore migration, Summer Flounder usually spawn in the fall and early winter. They are known to spawn several times through the season, creating a boom of Summer Flounder.

Spawning peaks in late October and early November. The main factors contributing to this are the changes in water temperature and the boom of autumn plankton. Females can carry 4,000,000 eggs, releasing them near the continental shelf.

Larval and post-larval flounder will feed on small crustaceans and zooplankton. Their diet changes to larger crustaceans and fish, eventually becoming opportunistic feeders as adults. Most of their adulthood is spent idle on the ocean floor, waiting for a meal.


The most common place to find the Summer Flounder is off of the Atlantic coast. The United States has many flounder fisheries dotting the coast from Maine to the coast of Florida.

You can also find Summer Flounder as far north as Nova Scotia. These fish will often become less plentiful the more north you go due to the ocean’s chill in the northern hemisphere. They are most common around the upper east coast of the United States.

Where Do Summer Flounder Live?

The Summer Flounder’s prime habitat lies between Cape Cod, Massachusetts, and Cape Fear, North Carolina.

Typically, it’s most common to find the Summer Flounder near the coast, where water is deep enough to conceal them but shallow enough for them to reach the ocean floor.

It’s rare to find a flounder swimming around far from the ocean floor. Staying close to the sand lets them remain safe and hunt easier.

Food & Diet

Summer Flounder are active predators that hunt via ambush. They are far from the top of the food chain and have multiple natural predators that will seek them out.

Read on for deeper information detailing the Summer Flounder’s place in the food chain, their prey, and their predators.

What Do Summer Flounder Eat?

The Summer Flounder primarily eat bony fish. However, they also fit many crustaceans and benthic invertebrates into their diets.

seagrass underwater for omnivorous Summer Flounder

Crabs, shrimps, and even squids make up the bulk of their diet. These flounder are also omnivorous, often found eating seagrass and phytoplankton if they cannot find other prey.

The Summer Flounder can hunt in two different ways, either by camouflage, laying in wait and ambushing prey, or chasing it down if the need arises. These fish can outswim most of their preferred prey.

Still, the Summer Flounder is an opportunistic feeder. That means they won’t be overly picky about a meal or hunt down something specific.

Typically, the Summer Flounder will eat whatever floats close enough for them to ambush. This hunting style makes it so that shellfish and crustaceans are their most common meals due to proximity to the seafloor.

The opportunistic feeding also makes it so that Summer Flounder don’t have a specific mealtime.

They eat when food is available and convenient, unlike some fish that may hunt specifically in the morning or night.

Threats & Predators

Despite their high place on the food chain, Summer Flounder have many threats and predators. Here are some of the most common threats to the fish’s safety.

Human Threats

Pollution is one of the most common threats to the Summer Flounder. Due to their proximity to the coast, oceanic runoff can significantly harm their habitats and even lead to mass death. Oil spills have often caused massive damage to their habitats.

One of the worst things humans do to Summer Flounder is deep-sea trawling. Trawling across the ocean floor causes massive damage to the seafloor habitat.

Summer Flounder frequently have their habitats ruined or are accidentally fished up in this method.

Climate Change & Global Warming

Changing oceanic temperatures pose an enormous threat to the Summer Flounder. Their spawning season is heavily affected by the temperature of the ocean.

Changing water temperatures due to global warming also affects the spawning of plankton that Summer Flounder eat during their larval stage, which can cause them to starve out in their youth.


Summer Flounder have many threats on the ocean floor. Monkfish, Codes, Four-spot Flounder, large sharks, and Spiny Dogfish are some of their most common threats. Once large enough, they can usually fend for themselves.

Other Threats

Summer Flounder live close enough to the coast to be affected by several other threats. Pollution from construction or trash from crowded beaches can often find its way into their habitats, ruining them quickly.

Conservation Status

As of 2021, Summer Flounder are not overfished and not expected to be in the future. The stock declined in the 1980s but has since returned due to sustainable practices and conservation efforts.

According to scientists at the Northeast Fisheries Science Center, the Summer Flounder is far from endangered and has a high population.

Fun Facts About Summer Flounder

  • Summer Flounder eat flora less and less the larger they grow but subsist off of phytoplankton almost entirely as larvae
  • Fertilization of Summer Flounder eggs takes place entirely outside of the body.
  • Females release up to a million eggs multiple times during the spawning season
  • Summer Flounder eggs hatch within a few days after spawning if adequately fertilized and grow quickly after hatching
  • The majority of the larvae survive, having a higher survival rate than many other fish
  • There is no different name for male or female Summer Flounder
  • Summer Flounder are not a potential threat to humans and will not attack, but may harm someone if handled incorrectly
  • Summer Flounder are commonly kept as pets

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