Freshwater moray facts for kids
Quick facts for kids Freshwater moray eel |
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| Conservation status | |
| Scientific classification | |
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| Genus: |
Gymnothorax
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| Species: |
G. polyuranodon
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| Binomial name | |
| Gymnothorax polyuranodon (Bleeker, 1854)
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| Synonyms | |
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Muraena polyuranodon Bleeker, 1854 |
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The freshwater moray eel (Gymnothorax polyuranodon) is a type of moray eel. It lives in the Indo-Pacific region. You can find it in places like Sri Lanka, the Philippines, Indonesia, Papua New Guinea, and northern Australia. It also lives around many islands in the western Pacific Ocean.
People call it by other names too. These include the many-toothed moray and the spotted freshwater moray. Sometimes it's called the blackspotted moray or tiger freshwater moray.
Contents
Description
The freshwater moray eel was first named by Pieter Bleeker in 1853. This eel can grow up to 1.5 meters (about 5 feet) long. However, most are usually smaller than 1 meter (about 3 feet).
Its body is yellow or light tan. It has dark brown spots and blotches all over. This eel has very small teeth compared to its head size. Like all moray eels, it eats meat. It mostly eats fish. Sometimes it eats shrimp, clams, and worms. It prefers to eat live food.
Moray eels have poor eyesight. But they have an amazing sense of smell. This eel can be a bit aggressive. Its spit is slightly toxic. A bite from this eel won't kill you. But it can be very painful. The bite might also get infected.
Habitat
The freshwater moray eel lives in shallow waters. It often stays in water that is only 3 meters (about 10 feet) deep or less. You can find it in shallow ocean waters near the coast. It also lives in estuaries, which are where rivers meet the sea. It can even swim a short distance up rivers.
For a long time, people thought this "freshwater" moray eel was mostly a sea creature. They believed it could only handle fresh water for short times. But new information suggests something different. The Gymnothorax polyuranodon might be a catadromous species. This means it spends most of its life in fresh water. Then, it travels to saltwater to lay its eggs.
Young eels are born in the ocean. After hatching, they move into fresh water to grow up. When they are ready to have babies, the adult eels swim back to the ocean. Very young eels, called elvers, are not seen in fresh water. There is only one record of an elver found in saltwater.
Young eels often live in brackish water. This is water that is a mix of fresh and salt water. They especially like mangrove forests. They hide there to stay safe from bigger fish. Adult eels are often found in fresh water. But it's possible they only stay there for a short time.
In northeastern Australia, scientists watched these eels for three years. Most of the eels, about three-quarters, liked calm pools. They also preferred slow-moving water. These spots had many large rocks where the eels could hide.
Aquarium trade
The freshwater moray eel is not very common in the wild. It has also been rare in the pet trade. But recently, more people are interested in keeping them. Scientists are also studying them more. This eel has been the topic of several scientific papers. It is also appearing more often online for sale. Still, it's not as common as other types of eels.
If you want to keep this eel, you need a big tank. Because it grows large, the tank should be at least 150 gallons. A bigger tank is even better. Moray eels have very soft skin. It can get hurt easily by sharp things. So, don't put broken shells or rough gravel in the tank. The bottom of the tank should have sand or smooth, rounded gravel.
The tank also needs many large rocks. These rocks should have lots of openings and overhangs. This gives the eel places to hide. The water flow in the tank should be low. This eel is a tropical species. So, the water temperature should be kept between 24-28 Celsius (75-82 Fahrenheit).
People who keep these eels have learned a lot. One important thing is the confusion about it being a "freshwater" species. Because it's often sold as a "freshwater" eel, buyers think it can only live in fresh water. This is not true. This eel can live in pure saltwater, pure freshwater, and mixed brackish water.
Information about whether it can live long-term in fresh water has been unclear. Some sources say it won't live long in fresh water. But a few studies don't agree with this. One study looked at four eels. It suggested that these eels likely lived in fresh or brackish water their whole lives after being born. The study said that this eel can live in fresh water for a long time. This is shown by people keeping them in freshwater aquariums. It's also shown by finding them in freshwater habitats.
Another study checked if this eel could grow and survive in a freshwater aquarium. They kept four eels in a 1200-liter freshwater tank. The eels grew a lot over a year. This shows they can survive and grow well in fresh water. This finding, plus more observations of adult eels in rivers, suggests they might live in rivers for a long time.
Some people thought that less salt in the water would make the eel eat less. They thought it might even stop eating in fresh water. But the study mentioned above proves this wrong. The eels grew while living in a freshwater tank for a year. People on fish forums also say they have kept these eels in fresh water for a long time without problems.
Another thing aquarists have noticed is that each eel is different. They have their own personalities. So, their behavior can be a bit unpredictable. Some people can keep many eels in one tank. They might not fight or compete much. But other eels can be aggressive and territorial. Some eels will get along with other fish in the tank. Others will snap at or even eat any other fish.
Because this eel can be aggressive and eats live fish, don't keep it with small fish. They will probably be eaten. It's best to keep this eel with bigger fish. Or, you can keep it in a tank by itself. If the eel is well-fed, it's less likely to attack other fish. One study showed that a well-fed eel usually didn't eat again for 24 hours. If you keep eels of similar size together, they usually get along.
This eel prefers live food. When you first get it, it might only eat live food. But you can teach it to eat prepared foods. These can be pieces of shrimp, fish, or mussels.
Most moray eels are active at night. So, the best time to feed them is in the evening. Morays hunt by smell. If you put too much food in the tank, the eel might get confused. It won't know where the smell is coming from. So, it's best to feed them small amounts directly. Give them pieces of meat no bigger than their head.
Because they have poor eyesight and toxic spit, don't hand-feed them. Use a feeding stick instead.
A related eel, the Indian Mud Moray Eel, can be harmed by copper-based medicines. So, if you own a freshwater moray eel, be careful with copper medicines. They might have bad effects on your eel too.
If you want to breed these eels, you must do it in a saltwater aquarium. They likely do not breed in fresh water.
Like all moray eels, this species does not like to be stuck in a tank. It will try to escape. So, the top of the aquarium must be tightly closed. This eel can squeeze its body through very small gaps.
See also
In Spanish: Gymnothorax polyuranodon para niños
