Snakehead Fish: Invasive Predators in North America - Owlcation - Education
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Snakehead Fish: Invasive Predators in North America

Linda Crampton is a writer and teacher with an honors degree in biology. She loves to study nature and write about living things.

What Is a Snakehead?

Snakeheads are predatory fish that have some surprising characteristics. The giant snakehead is a voracious predator with sharp teeth, a large mouth, and strong jaws. It's been called a "frankenfish" due to its aggressive reputation. It has a lung-like organ in addition to gills and can breathe in air. The fish is able to survive out of water for several days. It travels over land with a wriggling motion and moves up to a quarter of a mile to reach a new waterway.

Other snakehead species don't seem to be quite as aggressive or as capable of moving on land as the giant snakehead. They are all fierce and very capable predators, however, and they can all breathe in air.

Snakeheads are native to Asia and Africa. They have been transported to North America for the pet trade and for food stores that sell living fish. The animals have appeared in some U.S. and Canadian waterways, presumably because they were released from home aquariums. Their presence in the wild is very worrying. They have no natural predators in North America and may be a serious threat to native wildlife.

Identifying a Snakehead Fish

Snakeheads have an elongated body. Different species exhibit different color patterns. Fin placement and appearance is the same in all of the species, however. It's one method used to identify invasive snakeheads in North America.

The fish have a long dorsal fin on their back, as shown above. The pectoral fins are located on their sides behind their head. The pelvic fins are located on the undersurface almost directly below the pectoral fins. The anal fin is located on the undersurface towards the rear of the animal and is generally about two thirds of the length of the dorsal fin. Like other fish, snakeheads have a caudal (tail) fin at the end of their body.

There are two genera of snakeheads. Member of the genus Channa live in Asia, Indonesia, and Malaysia. The genus Parachanna is found in Africa. The video below shows the peacock snakehead, or Channa pulcra.

Fish That Can Breathe in Air

The head of a snakefish has enlarged scales. The eyes are often shifted towards the front of the head. These features resemble those of a snake, giving the fish their name.

Snakeheads obtain oxygen from air as well as water. The animals use their gills to obtain oxygen from water, just as other fish do. Water enters their mouth and travels to the gills on both sides of the body. Oxygen passes from the water into the gill tissue and then enters blood vessels. The water leaves the gills through the opening behind the operculum (the bony flap that covers each gill chamber).

To breathe in air, the fish use a space in their head above their gills called the suprabranchial chamber or the suprabranchial organ. Air that the fish gulps from the water surface enters the suprabranchial chamber. Here oxygen from the air passes into blood vessels in the tissue lining the chamber.

The suprabranchial chamber of a snakehead is quite similar to the labyrinth organ found in some other air-breathing fish. Examples of labyrinth fish include the Siamese fighting fish, the climbing perch, and many types of gouramis.

The Giant Snakehead

The giant snakehead (Channa micropeltes) lives in freshwater, like other snakeheads. Living up to its name, it may reach more than 3.3 feet (a meter) in length and weigh over 44 pounds (20 kilograms).

The fish is quite variable in appearance. It has a dark grey, blue-black, or black background color with white, silver, or blue-green markings. The undersurface of the fish is much lighter in color than the rest of the fish.

The giant snakehead is also known as the red snakehead. This name comes from the color of the young fish, or fry. In some parts of the world, fisherman refer to the giant snakehead as a toman. It's a popular prey in sport fishing and is also enjoyed as an edible fish in some countries.

The fish has a reputation as a fearsome and even vicious predator. Its diet consists mainly of other fish, but it also eats frogs, crustaceans, and even birds. It reportedly kills more animals than it eats.

Giant snakeheads create a nest by clearing a cylindrical area in the middle of aquatic vegetation. When the eggs are laid, they rise to the top of the water column and are carefully guarded by the adults. The parents also guard the fry, which helps the youngsters to survive.

A fry of the giant snakehead; the young fish is about two weeks old

A fry of the giant snakehead; the young fish is about two weeks old

The Northern Snakehead

Although they are classified in the same genus, the Northern Snakehead (Channa argus) and the giant snakehead look quite different from one another. The northern snakehead is an attractive animal that has a tan, brown, grey, or grey-green background color decorated with darker blotches and stripes. The body is torpedo-shaped, and the top of the head is noticeably flattened. The lower jaw of the fish protrudes beyond its upper jaw.

The northern snakehead is native to China, Korea, and Russia and has spread to other areas of Southeast Asia. It lives in areas where the water is muddy and is flowing slowly or is stagnant. It feeds mainly on other fish but also eats crustaceans and insects. Like the giant snakehead, it's often described as "ferocious". The species is an obligate air breather—it must breathe air as well as absorb oxygen through its gills in order to survive.

There is some debate about how capable the fish is at moving over land. There are claims that it can travel on land and survive for three or four days out of water, provided it stays moist, just like a giant snakehead. Many researchers say that it can't move far when it leaves the water and that under normal circumstances it can survive for only a few hours in air, however.

Reproduction

There is still a lot to learn about the life history and reproduction of the northern snakehead. Understanding the fish's habits is essential in order to control its population when it becomes invasive.

In 2007, a northern snakehead nest was discovered in the Potomac River in the United States. The nest was a cylindrical column of water surrounded by an aquatic plant called Hydrilla. A circular mat of Hydrilla formed a canopy or roof on top of the nest. Orange-yellow eggs had been laid on the canopy. The eggs weren't adhesive and were held in place and hidden by the plant leaves and stems. The adults—both the male and the female—patrolled the water underneath the canopy.

Northern snakehead nests have been found in other areas, too. They have all been cylindrical nests surrounded by vegetation and have been about one meter in diameter. These nests have lacked a canopy, however.

The fish have a high fecundity and lay 22,000 to 115,000 eggs at a time. They breed up to five times a year. Although some of the eggs and fry die, parental care likely improves reproductive success compared to the situation in fish that don't guard their young.

Wild Snakeheads in North America

Wild snakeheads, including giant snakeheads, are sighted periodically in various parts of North America. In at least three areas, snakeheads have formed a resident population and are reproducing.

The northern snakehead is found in the Potomac River and its tributaries in the state of Maryland. The bullseye snakehead (Channa marulius) has established itself in part of Florida. The adults of this species frequently have red eyes and a black spot surrounded by orange at the base of their tail fin. The blotched snakehead (Channa maculata) lives in Hawaii and is quite similar in appearance to the northern snakehead.

Snakeheads are thought to have entered the wild when they were released from home aquariums, perhaps when they grew too large or too expensive to keep. They may also have been released into ponds by fish sellers or other people who hoped that the animals would reproduce to produce a convenient and free source of edible fish.

The northern snakehead has established itself firmly in the Potomac River system, with a population estimated at somewhere above 21,000 individuals, ranging through more than 120 river miles (200 kilometers).

— National Geographic

An Invasive Snakehead in Burnaby, British Columbia

I live in British Columbia. In 2012, a snakehead fish was found living in a pond located in Central Park in Burnaby, BC, not far from my home. (The fish is shown in the video below.) It was caught when the pond was partially drained.

There were concerns that the fish was a northern snakehead, which would have been capable of living through a southwestern BC winter. In November 2013, however, the fish was identified as a blotched snakehead. This species would be unlikely to survive through the local winter, which although mild in terms of Canadian winters is much colder than the climate in the snakehead's native habitat.

If the fish had survived and reproduced, native fish may have been eaten and their populations harmed. Researchers said that there was no evidence that the animal had reproduced, however. They also said that it likely survived by eating other non-native species placed in the pond, such as goldfish and fathead minnows. No more wild snakeheads have been discovered in the province since the 2012 discovery, to the relief of many British Columbians, including me.

Dangers of Invasive Populations

The presence of wild snakeheads in North America worries some conservation officers and officials very much. The fish have no natural predators. There is talk of horrible scenarios such as native animal species being wiped out by the fish. Snakeheads may not only prey on native animals but also pass parasites to them.

The presence of any invasive species—especially a predator—must always be taken seriously. Snakeheads definitely have the potential to create an environmental problem. The areas that they have invaded need to be monitored closely. It may only be a matter of time before serious effects are noticed due to the presence of the fish. At the moment, though, it's not clear how much damage snakeheads are causing to their ecosystem and how significant or widespread any damage is.

In Maryland, officials have enlisted the aid of the public in the effort to control the northern snakehead population. They are advertising the tastiness of the animal's flesh to encourage fishing and are holding sports fishing competitions.

In general, snakeheads aren't dangerous to humans. The only times they may show aggression towards us is when they're disturbed while they're protecting their eggs or young and when they're caught. There have been reports of quite serious injuries caused by giant snakehead bites in these situations.

The Future for the Fish in North America

Single snakehead fish are generally quickly removed by authorities once they're discovered. Once reproduction has occurred and a population has formed, however, removing the fish is difficult or even impossible, especially when the population is distributed over a wide area. As some people have said, the snakeheads in the Potomac River system are likely here to stay,

The outcome of the snakehead presence is unknown. Will the dire predictions of conservationists come true? Will we be able to avoid these consequences if we keep the snakehead population under control? Are we overreacting to the presence of snakeheads, as a few people have suggested, or are they actually as dangerous for the environment as many scientists say? These questions can't be answered yet. It may take years to find the answers, which is why caution is needed in the present.

References

  • Information about snakeheads: a PDF document from the USFWS (US Fish and Wildlife Service)
  • How to distinguish a snakehead from other fish in North America from the Wisconsin government
  • Facts about giant snakeheads from the USGS (United States Geological Survey)
  • Northern snakehead information from New York Invasive Species Information
  • Investigating a nest of the fish in the Potomac River catchment area (Abstract) from BioOne and Northeastern Naturalist
  • A description of the animal's population in the Potomac River system from National Geographic
  • Discovery of a blotched snakehead in Burnaby from the Vancouver Sun newspaper

Questions & Answers

Question: How does the labyrinth organ work?

Answer: The labyrinth organ is located above the gills. It contains bony plates that are covered with a thin membrane that contains blood vessels. The blood absorbs oxygen from the air that the fish gulps from the surface of the water.

Question: Is it legal to own snakeheads?

Answer: I don’t know where you live, so I can’t tell you whether it’s legal to keep a snakehead fish as a pet in your part of the world. In my location (British Columbia in Canada) it no longer is. In fact, according to the Royal British Columbia Museum, it’s illegal to import, possess, breed, or transport any member of the family Channidae in British Columbia. You will have to contact your local authorities to check the law where you live.

Question: My friend was part of the team that drained the lake. People complained and no native species were found at all in the lake, l believe. Have more of Snakeheads been found? What are Snakeheads said to taste like?

Answer: As far as I know, no more snakeheads have been found in Burnaby. I've never eaten the fish, but they are said to have a mild taste.

Question: Who are the relatives of a snakehead fish?

Answer: Snakehead fish belong to the class Actinopterygii (ray-finned fish) and the family Channidae. The family contains two genera: Channa, which is found in Asia, and Parachanna, which is found in Africa. The family belongs to the order Anabantiformes. The species in this order are freshwater fish. Two examples are the giant gourami (Osphronemus goramy) and the climbing perch (Anabas testudineus), which are both native to Asia.

© 2013 Linda Crampton

Comments

Linda Crampton (author) from British Columbia, Canada on February 02, 2016:

Thank you very much, Taranwanderer. I appreciate your kind comment.

Taranwanderer on February 02, 2016:

You always write such excellent and informative articles, as I have noticed. Great work...strange to think that such a small animal can cause so many issues.

Linda Crampton (author) from British Columbia, Canada on October 31, 2015:

Thank you very much, Prince.

Prince on October 31, 2015:

Wonderful Info.

Linda Crampton (author) from British Columbia, Canada on June 14, 2014:

Hi, Peg. Yes, I can see why the term "creepy" could be applied to snakehead fish! They are interesting animals, though. Thank you very much for the comment.

Peg Cole from Northeast of Dallas, Texas on June 14, 2014:

Enjoyed learning more about these snakehead fish and their origins. They're really creepy. I'm not sure I'd want to eat them. The pictures are interesting and the fact that they can breathe air is really strange, sort of like some evolutionary missing link.

Linda Crampton (author) from British Columbia, Canada on February 10, 2014:

Hi, ologsinquito. Yes, predatory fish that can migrate over land could be a big problem! Thanks for the visit.

ologsinquito from USA on February 10, 2014:

I hope these fish can't get very far on land, because it would make it more difficult to contain them in one body of water. They sound almost like invasive monsters.

Linda Crampton (author) from British Columbia, Canada on December 17, 2013:

Hi, Deb. Thanks for the visit. It is very interesting that snakeheads can breathe air and move on land. They do seem a little like mammals, even though they are really fish! They aren't known to hunt on land, but they could certainly pose a danger for animals that live in or on the water.

Deb Hirt from Stillwater, OK on December 17, 2013:

Seems to me if these snakeheads are invasive, then they could well be detrimental to the well-being of other fish. Since they are part mammalian, that makes them even more dangerous, as they can harm both water and land species.

Linda Crampton (author) from British Columbia, Canada on December 15, 2013:

Hi, Christy. Thanks for the comment! The Burnaby snakehead was killed and preserved. It's at the B.C. Museum in Victoria now, but I don't know if it's on display yet.

Christy Birmingham from British Columbia, Canada on December 15, 2013:

I had no idea that snakeheads could breathe air - your description of that was interesting. I like that you brought in the local BC element too. I'm only a few hours from Burnaby so I will have to check the snakehead there out soon!

Linda Crampton (author) from British Columbia, Canada on December 14, 2013:

Thank you very much for the comment, Dianna. I hope that the authorities in Florida are on top of the situation, too!

Dianna Mendez on December 14, 2013:

I see from your post that we have them here in Florida and hope that the authorities are on top of this invasion. I don't know how you do it, but you have shared another new topic with great interest!

Linda Crampton (author) from British Columbia, Canada on December 10, 2013:

Hi, drbj. Thanks for the comment. I can understand why you don't want to meet a snakehead! They are amazing, but they do have their drawbacks!

drbj and sherry from south Florida on December 10, 2013:

Amazing creatures, Alicia, but I don't want to encounter them in person either on land or in the sea. Thanks for all this fascinating information.

Linda Crampton (author) from British Columbia, Canada on December 10, 2013:

Hi, Crafty. Yes, it does seem like a good deal (although I don't know how much the fishing licences cost)! Thank you very much for the comment.

Linda Crampton (author) from British Columbia, Canada on December 10, 2013:

Hi, vespawoolf. I hope very much that the snakehead population is kept under control, too. The presence of invasive species in the environment is a big concern. Thanks for the visit.

CraftytotheCore on December 10, 2013:

That is so interesting. I would think more people would take advantage of fishing for them. It's sort of like free food in a way if they are that plentiful and just the cost of a fishing license (and open airtime outdoors).

Vespa Woolf from Peru, South America on December 10, 2013:

How sad that another non-native species has interrupted the natural balance of things. How interesting that it can breathe oxygen and it does sound like a voracious predator. I hope something can be done to check their population. Thank you for sharing.

Linda Crampton (author) from British Columbia, Canada on December 10, 2013:

Hi, Jodah. Thanks for the visit. The lung fish is very interesting, too! Nature is fascinating.

Linda Crampton (author) from British Columbia, Canada on December 10, 2013:

Hi, Pamela. Thanks for the comment. Yes, the snakehead is certainly an unusual fish!

John Hansen from Queensland Australia on December 10, 2013:

This was a very interesting and quite in-depth hub of the snakehead. I enjoy reading about different animals, fish and birds, and enjoyed ths very much. We don't have snakeheads in Australia, but do have an air breathing fish, "the lung fish", however it is endangered and isn't as ferocious as the snakeheads.

Pamela Oglesby from Sunny Florida on December 10, 2013:

This is really a very interesting hub. I can't say the snakehead is exactly attractive, but he is certainly an interesting creature. Thanks for providing a little education for us on an unusual creature.

Linda Crampton (author) from British Columbia, Canada on December 09, 2013:

Hi, Writer Fox. Yes, it is fascinating that some fish can breathe in air. Snakeheads are interesting fish, but I don't want them in my local waterways! Thanks for the vote.

Linda Crampton (author) from British Columbia, Canada on December 09, 2013:

Thank you for the comment and all the votes, DDE! I appreciate your visit.

Writer Fox from the wadi near the little river on December 09, 2013:

It's amazing that this fish can survive out of the water. From your article it does seem like this species is one you wouldn't want in your favorite fishing hole! Voted up!

Devika Primić from Dubrovnik, Croatia on December 09, 2013:

Snakehead Fish - Invasive and Voracious Predators has a lovely photos and an interesting video with fascinating facts voted up, interesting useful and awesome.

Linda Crampton (author) from British Columbia, Canada on December 08, 2013:

Thank you very much for the comment, the vote and the share, Bill. Yes, these fish are both fascinating and scary at the same time! It will be interesting to see what the future holds for them in North America.

Bill De Giulio from Massachusetts on December 08, 2013:

Oh my, invasion of the Snake Heads. Had not heard of this species, very interesting and a little scary. Great job Linda, lots of interesting information on this species. Voted up, shared, etc...

Linda Crampton (author) from British Columbia, Canada on December 08, 2013:

Hi, Bill. You've described the attitude that many people have towards snakeheads beautifully! They are worrying but interesting fish.

Bill Holland from Olympia, WA on December 08, 2013:

Nasty little buggers, aren't they? My goodness, I'm sure glad I don't swim where they are. I'd keep hearing the theme music from "Jaws" and worrying about being devoured. LOL

Linda Crampton (author) from British Columbia, Canada on December 07, 2013:

Hi, Rebecca. Yes, the world of nature - including snakeheads - is certainly fascinating! Thanks for the comment.

Linda Crampton (author) from British Columbia, Canada on December 07, 2013:

Thank you very much for the comment, the vote and the share, Faith, especially so soon after I published the hub! Yes, the potential effects of snakeheads are scary. Decimation of a native species is a worst-case scenario. Hopefully this won't happen. Time will tell! Best wishes to you.

Rebecca Mealey from Northeastern Georgia, USA on December 07, 2013:

The seas and lakes carry so many wonders Thanks for sharing such interesting information about the snakehead fish.

Faith Reaper from southern USA on December 07, 2013:

Yikes!!! What a nasty looking creature and looks like not a good one to be reproducing and taking over in North America! It is scary to know they can wipe out other species altogether! I hope they find an answer to contain these snakehead fish.

Up +++ and sharing

Fascinating hub and on a topic I have never heard of before too.

Blessings, Faith Reaper