Fun Candiru Facts For Kids

Moumita Dutta
Nov 14, 2022 By Moumita Dutta
Originally Published on Aug 05, 2021
Edited by Jacob Fitzbright
Fact-checked by Abdulqudus Mojeed
Candiru facts are interesting

A candiru is a type of parasitic catfish that preys on other fish, animals, and humans. They are freshwater fish and are prevalent in the Amazonian basin. Generally, the candiru fish has a translucent and cloudy color. After feeding, they may acquire a greyish or brownish hue.

Its gills are covered with spikes which it uses to latch on to its prey. They are found in the gills of larger fish. In some cases, they have been known to latch on to animals and humans.

The hematophagous candiru can travel all the way up the urinary tract of an animal and reach the urethra. However, to date, there has been only one confirmed case of a candiru attaching itself to a human.

The largest candiru fish ever recorded to date was 16 in (40 cm) long! In many ways, the candiru bears a close resemblance to an eel, though it is smaller. So, for more interesting facts about candiru fish, read on.

To know more about similar animals, check out the electric eel and the cobia. 

Candiru Interesting Facts

What type of animal is a Candiru?

The candiru is a type of parasitic catfish.

What class of animal does a Candiru belong to?

The candiru fish belongs to the class of ray-finned fishes or Actinopterygii.

How many Candirus are there in the world?

The candiru fish has had little contact with humans. As such, there is no documentation of their exact numbers. It is known that there are over 136 species presently.

Where does a Candiru live?

The candiru (Vandellia cirrhosa) is found in murky and shallow waters of North and South America.

What is a Candiru's habitat?

The preferred habitat of the candiru catfish is the Amazon river basin and the Ornico river basin. As they do not possess appendages, they cannot jump out of the water or swim against a strong current.

Thus, they prefer to remain in shallow and slow-moving, acidic water. They burrow within the sandy bottom when not feeding or performing other activities.

Who do Candirus live with?

The candiru fish live solitary lives, latching onto the body of their agent when needed.  

How long does a Candiru live?

Not enough study has been done to gauge the life span of a candiru. There has been only one instance of them being born in captivity. However, their life span was not observed in this case.

How do they reproduce?

Among candiru vandellia, the male corners the female by swimming around her repeatedly. When the fishes come in lateral contact, the egg and sperm are released.

Their gestation period is not known. The female lays a batch of eggs that may contain anywhere from up to 15 eggs. The breeding activity takes place over three days.

Their breeding season is believed to be around December and the females lay eggs multiple times during each breeding season. The adult candiru fish do not take any care of their offspring or remain around to hatch them.

What is their conservation status?

The IUCN classifies the Trichomycterus papilliferus as being Endangered. Whereas the Cambeva stawiarski is classified as an animal of Least Concern. The species, Trichomycterus papilliferus, is included in the list of endangered animals under the Conservation of Endangered Species of aquatic and semi-aquatic Fauna in the Baixo Iguaçu Basin.

Candiru Fun Facts

What do Candirus look like?

Eels and Candirus share a similar body type.

*This image is that of an eel that looks similar to a Candiru.  

The candiru has a small head and a translucent body. After feeding, it acquires a blackish or brownish color and its belly appears distended. Due to its small size and cloudy body, it is difficult to spot in the murky waters. The parasitic catfish has a head covered with barrels. Its gill covers have spines pointing backward.

How cute are they?

Being a parasite, it is of little surprise that the candiru scores very low on the cuteness scale. They are slimy, long, and have spiky heads. They also have very large eyes when compared to their small size. After feeding, their belly becomes disproportionately extended like a mosquito's.

How do they communicate?

The candiru (Vandellia cirrhosa) has huge eyes as compared to its body. Hence, it is believed that they rely on visual cues.

Generally, they can sense nitrogen-rich water, which is water expelled by the gills of larger fish. However, they may often confuse this with ammonia (in sweat and urine) which has a nitrogen component. Similar to amphibians, the candiru has a lateral line system that helps it to sense movements in the water.

How big is a Candiru?

The average size of the candiru (Vandellia cirrhosa) is only 2-7 inches. This means they are approximately the same size as salamanders or a Marmoset monkey.

How fast can a Candiru swim?

The candiru is an extremely agile and fast swimming fish. However, there are no proper measurements of their exact speed.

How much does a Candiru weigh?

The weight of an individual candiru fish is not known as these animals have not been studied in captivity.

What are their male and female names of the species?

The candiru fish is known as the cañero or candirus. There is no specific name for the male and female of the species.

What would you call a baby Candiru?

Candirus hatch from eggs. There is no specific name for their offspring.

What do they eat?

Generally, candirus drink fish and animal blood. However, some candiru species are pretty harmless. They burrow at the bottom of muddy rivers and feed on insect larvae and protozoa.

Are they dangerous?

The feeding habits of candiru make them dangerous. Once inside a gill, they bite off the gill filament and enjoy the blood flow.  The spikes on their gills can cause inflammation within the urinary tract and lead to a hemorrhage in animals and humans. Candiru attacks may result in death if such hemorrhages are left untreated.

Would they make a good pet?

Absolutely not! As a parasite, the Vandellia cirrhosa attacks animals, including humans, if given the chance. Moreover, they are not sentient enough to be a good companion. They can also swim and turn fast, making them very difficult to catch.

Did you know...

The backward spines on a candiru fish actually prevent it from being extracted or being pushed backward in a tunnel.

A general blood-feeding session may last from half a minute to over two minutes. In the case of fish, the candirus leave the fish once done and go back to their muddy burrow.

What makes the Candiru a parasite?

The candiru fish wait for larger fish to open their gills. They then bite off the gill filament and latch on to the operculum with their spines. Their prey includes various species of catfish as well.  Generally, people swimming in the Amazon River wear tight clothing to avoid any contact with them.

Gross facts and myths about the Candiru

It was earlier believed that the candiru is attracted to urine and sweat (ammonia compounds). But this theory was proven wrong in 2001 when experiments on the feeding behavior of the candiru fish actually were conducted.

It showed that they gave no reaction to chemicals added to their water tank. Rather, they were attracted to nitrogen-rich water. The water flow created by urine might also have confused them into thinking it was a fish's gill.

Here at Kidadl, we have carefully created lots of interesting family-friendly animal facts for everyone to discover! Learn more about some other fish including the moray eel and the fluke fish.

You can even occupy yourself at home by drawing one of our candiru coloring pages.

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Written by Moumita Dutta

Bachelor of Arts specializing in Journalism and Mass Communication, Postgraduate Diploma in Sports Management

Moumita Dutta picture

Moumita DuttaBachelor of Arts specializing in Journalism and Mass Communication, Postgraduate Diploma in Sports Management

A content writer and editor with a passion for sports, Moumita has honed her skills in producing compelling match reports and stories about sporting heroes. She holds a degree in Journalism and Mass Communication from the Indian Institute of Social Welfare and Business Management, Calcutta University, alongside a postgraduate diploma in Sports Management.

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Fact-checked by Abdulqudus Mojeed

Bachelor of Law

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Abdulqudus MojeedBachelor of Law

A versatile professional with a passion for creative writing and technology. Abdulqudus is currently pursuing his Bachelor of Law from the University of Lagos and has experience as a tutor, intern assistant, and volunteer. He possesses strong organizational skills and is a detail-oriented person.

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