The Atlantic tarpon (Megalops atlanticus), is a prehistoric fish, one of only two in the Megalops genus. This migrating bony fish can grow over 8ft long and weigh 350 pounds. It has a huge mouth and greatly enhanced vision to make it a powerful predator. The fish is fast, agile, and always on the move. Recreational fishing has hurt the population in recent decades. But these living fossils have fascinating, ever-changing lives when they are not being hunted.

1. Tarpons swim as fast as 35 miles per hour, and leap as high as ten feet in the air.

Tarpons don’t let their size slow them down. They can swim 56 km/h (35 mph)! Swimming so fast gives them the momentum to leap 10 feet in the air! When a tarpon is caught on a hook, it will swim as fast as it can and leap in order to free itself. Being so fast and agile also helps it evade its much larger predators. It also makes it easy to catch smaller, fast-moving prey.

2. Tarpon teeth are so small that the fish swallows prey whole instead

Adult tarpons are carnivores. They mostly eat crabs and other fish. You would think any animal that eats crustaceans would have the power to crush their strong shells. But a tarpon’s teeth are too small to bite into prey. Luckily, they have large, upturned mouths that enable them to swallow their entire prey. Their mouths are connected to the gills so they can suck up prey just from inhaling, like a large, slippery vacuum cleaner.

Tarpon Feeding
Image by Wendy Harman

3. Sharks, alligators, and porpoises prey on tarpon

Tarpons are big, but its natural predators are even bigger. Sharks, alligators, and porpoises all prey on tarpon. Atlantic tarpon spend much of their young lives migrating through fresh and brackish water. A tarpon travelling through a Florida swamp could easily fall prey to a ferocious alligator. And fishermen have watched helplessly as the big tarpon they are about to reel in suddenly gets stolen by a shark!

4. Tarpons taste disgusting to humans, but they are the most targeted fish in America’s $6 billion catch and release industry

Unlike sharks, humans don’t find tarpon so tasty. Humans can eat tarpon, but it won’t be a pleasant meal. Even though these fishermen have no use for tarpon, they still target it more than any other fish in the United States. The catch and release fishing industry is worth $6 billion. Nearly all of the tarpon are wounded when they are thrown back into the ocean, and die shortly after.

Tarpon fishing
Image by GIPHY

5. The Atlantic tarpon finished evolving 18 million years ago.

Fossils of Atlantic tarpon from 18 million years ago perfectly match the Atlantic tarpon living today. This means that 18 million years ago, the fish stopped evolving. It has remained the same ever since. Species are always evolving to survive in the wild, so the Atlantic tarpon has been perfectly fit for its habitat for all that time!

Atlantic Tarpon
Image by Kris-Mikael Krister

Fossils for the megalops genus date back over 100 million years

Tarpons belong to the megalops genus. The earliest known megalops fossils are over 100 million years old!  This fish dates back to the Cretaceous Period, and swam while dinosaurs roamed the land. And since they are so primitive, tarpons are bony fish. This means their skeletons are made of bone tissue. More recent fish have skeletons made of cartilage. 

6. If an environment doesn’t have enough oxygen, a tarpon will gulp air from the surface

Tarpens spend much of their youth in waters with very little oxygen. Water that is low in oxygen does not have as many predators as the open ocean. However, sometimes there isn’t enough oxygen for tarpon to breathe through their gills. Luckily, their swim bladders are connected to their respiratory systems. If the tarpon is low on oxygen, it can swim to the surface and breathe in the same air as humans.

7. Adult tarpons can see ultraviolet light, but juveniles see better in murky waters

Like other migratory fish, tarpons have vision that changes as they grow. Because young and adult tarpons live in different habitats, their eyes develop accordingly. Juvenile tarpon are best adapted to seeing in murky waters. They can make out dark greens and blues. Adult tarpons live in clear, open waters. They have extra conical cells in their eyes so they can see ultraviolet light. UV light reflects off of many smaller fish, so tarpons use the light to detect prey.

Image by Kris-Mikael Krister

Tarpon eyes have a layer of cells reflective cells that maximize light

Tarpon eyes have a layer of cells called a tapetum. The tapetum is like reflective tape. It maximizes the amount of light the eyes can capture. Tarpons traveling through murky waters or hunting at night use this to “brighten” their environment (to them). This helps the tarpon detect prey before prey detects the predator. It is also why tarpon eyes glow in the dark.

Image by ictheostega

8. Female tarpons can shed up to 12 million eggs at once!

Tarpon are spawn breeders. To reproduce, tarpons travel to warm, offshore waters. Females release their eggs into the water, and males release their sperm. The sperm fertilizes nearby eggs. During spawning season, just one female tarpon can shed 12 million eggs at once.  

Female tarpons grow much larger than males because of the amount of eggs they carry

Female tarpons can be over 8ft long and weigh over 350 pounds! But males don’t grow as large. Scientists believe that females are larger to account for the amount of eggs they carry until spawning season. They need all that extra room to carry 10s of millions of eggs.

9. Tarpon develops in three stages, like eels

Baby tarpons go through three stages of development.

  1. Leptocephalus stage: This stage takes the first 2-3 months of a baby tarpon’s life. The larvae in this stage are transparent and almost flat. The leptocephali grow between 6-28mm (⅕-1”). To feed, larvae absorb nutrients from the water. This stage takes place 10-20m below the ocean surface. The water is warm, open, and clear.
Leptocephalus larva of a conger eel
Image by Uwe Kils
  1. Larvae stage: Larvae doesn’t grow in stage two, it actually shrinks! A 28mm larva shrinks to half that size! The larvae at this stage go down to 14mm. They shrink because they are metabolizing their own tissue! This stage takes about 70 days.  
  2. Juvenile stage: At day 70, the tarpon is now in the juvenile stage. This is when the real growth happens. Eating its own tissue is actually a smart idea, because the energy helps the tarpon grow. This stage lasts until the tarpon reaches maturity. Juvenile tarpon spend this stage in low oxygen waters, to keep safe from predators. And no, human readers, eating your own tissue will NOT help you grow.
Image by Matana_and_Jes

10. Female tarpons live for about 50 years, but males only live for 30 years

Female tarpons aren’t only bigger than males, they also live longer. Females usually live for 50 years. But males only live 30 years. Tarpons are slow growing fish, so they don’t reach maturity until they are 6-7 years old. By then, they are at least 4ft long. Many fishermen target juvenile tarpons because they are abundant in their special habitat and not as large as adults.

Image by Marsha Wheatley

The Shedd Aquarium in Chicago was home to a tarpon that lived 63 years!

One female tarpon lived over a decade beyond her peers. In 1998, this Atlantic tarpon living in the Shedd Aquarium in Chicago passed away at the ripe old age of 63! Remember, this fish was living in captivity. So it was safe from hungry predators and prideful fishermen. But many tarpons living in the wild still live for an impressive 50 years despite the dangers.

Maybe don’t mess with the Silver King

Fishermen have dubbed the Atlantic tarpon the Silver King because of the fish’s power. But if it is a king, then it probably isn’t a good idea to catch one and throw it back in the ocean to die. Regicide is the act of killing a monarch. And as Macbeth can tell you, it never ends well. On the other hand, an Atlantic tarpon allegedly once killed a human while it was being reeled in. A blow to the head from a thrashing tarpon’s massive body can be fatal for humans.

How endangered is this animal?

  • The International Union for Conservation of Nature now lists the Atlantic Tarpon as vulnerable.
  • The biggest threat to the Atlantic tarpon is recreational fishing.
  • Even though sportsmen in the United States practice catch and release, Atlantic tarpon frequently die soon after being released. When they are released, they can be disoriented, which makes them easy for predators to catch. They can also be fatally injured during a bout with a fisherman.
  • Their habitats are degrading due to climate change. Climate change can also change their migration patterns.



Also Known As

Silver king, Megalops


4–8 ft (1.2–2.4 m) long and weigh 60–280 lb (27–127 kg)


On both sides of the Atlantic Ocean


Are primarily found in coastal waters, bays, estuaries, and mangrove-lined lagoons within tropical, subtropical, and temperate climates


Fish and large crustaceans


Up to 50 years

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