The Candiru, Every Guy’s Ultimate Nightmare

The candiru may be as small as a toothpick, but the myth around the slender little fish is huge. A creature thin as a pencil lead, following a urine stream into the urethra of a man, where it erects spines and cannot be dislodged. Agg!

But is this centuries-old horror tale a myth?

One of over 130 species of parasitic freshwater catfish, the candiru can grow up to 40cm long. Most are 17cm. Some are 2.5cm and do have a diameter small enough to enter a urethra. They only live in the Amazon, especially in the murky, low-pH waters around the junction of Rio Negro, near Manaus.

The candiru, “uniquely occupied in doing evil”.


As with all parasites, candirus live off their host. Typically, they attach to the gills of larger fish. Using spines on their gills, the eel-like vampires cling to their prey causing inflammation, hemorrhage, then death.

The legend begins

The legend of a candiru entering the urethra of a urinating man first emerged in the 18th century. Reportedly, the smell of ammonia in urine attracted them. Guided by the smell, they’d swim to their victim –- a boy relieving himself in a river, for example –- and take flight into the tiny opening of the urethra. Around that time, the fish was described as “very small but uniquely occupied in doing evil”.

The wicked candiru.


Since then, evidence has shown candiru actually hunt by sight. They have no attraction to urine at all. But perhaps the story initially had a grain of truth. It is plausible that schools of candiru used their vision to follow the turbulent water around a man’s urine flow.

However, the first accounts of these parasites lodging within a human took place, surprisingly, in women.

The earliest report dates back to 1829. German biologist C. F. P. Von Martius only heard the story second-hand. From whom, no one knows. The local people of that region supposedly wore jock straps made of coconut shells when they bathed in the river as a preventive. Then in 1836 came the first actual report of a candiru entering the human body.

Female victims

A local woman needed the fish extracted from her urethra using the medicinal jagua plant. We never learned how it got in there in the first place. A second case occurred in 1891. By 1930, there were several similar cases. But no lodgings within other cavities.

The myth spread globally. From rural corners of New Zealand to large cities in the United States, the legend of a tiny fish swimming into terrified boys’ penises has spread. Then in 1997, the myth took a dramatic turn.

A 23-year-old man claimed that a candiru had jumped from the water into his urethra as he urinated in knee-deep water in Itacoatiara, Brazil. The man –- intriguingly, known only as F.B.C –- hurried to Manaus for treatment. Here, a Dr. Anoar Samad performed a two-hour surgery to remove the fish from his body.

A modern ‘incident’

His was the first real claim in history. Intrigued, American marine biologist Stephen Spotte went to Manaus two years later to investigate. He returned highly suspicious of the claim. Here’s why.

When Spotte met Dr. Samad, he was offered photos, original VHS footage of the cystoscopy procedure, and given a preserved candiru fish –- allegedly the one removed from the victim.

First, Spotte noted that the fish was 11.5mm in diameter – too wide to enter the urethra without significant force to pry the urethra open. That would be impossible because candiru don’t have appendages or other apparatus.

The victim claimed that the fish “leaped” out of the water. But Spotte concluded that “leaping” could not have allowed sufficient leverage to force its way inside.

Furthermore, Dr. Samad stated the candiru chewed its way through the ventral wall of the urethra into the patient’s scrotum. But Spotte noted that the candiru’s teeth aren’t strong enough to chew through such tissue.

The preserved candiru which Dr. Samad kept had all its spikes intact too, which contradicts Dr. Samad’s claim of having to snip the candiru’s grasping spike, for removal. If the fish was removed (as the VHS footage implied), the spikes would not have been intact.

A peculiar video

The five-minute video of the procedure is grainy. In it, there is no telltale sign of exactly what body part the fish is in or even if it is a fish at all. But more than four million people have watched the video online. Not surprisingly, Dr. Samad and F.B.C’s story were also featured on an episode of River Monsters.


Even if F.B.C was telling the truth, it is impossible for candiru to leap out of the water like a miniature javelin and score a bull’s eye into the urethra.

Part of the legend also suggested that if someone were to have the fish painfully lodged inside, the only way to remove it is by amputation. That’s because the spines on the candiru’s head make them too difficult and painful to remove. Unusual reports of scores of people with amputated penises in the Amazon seemingly confirm the candiru’s legend. But it’s more likely that those amputations are due to piranhas, not candiru.

So, can men safely pee in candiru-infested rivers? Only if piranhas are not there, too.

Chasing Dreams Travel

Alex Myall is a writer for ExplorersWeb. She has been writing about exploration and historical expeditions for four years. Previously she wrote about the human body in relation to exercise for publications and websites based in New Zealand. She also wrote modules for the Zealand Certificate of Exercise, Level 4. Based on Wellington’s South Coast, New Zealand, Myall is a full-time mother of two young girls, an enthusiastic trail runner, and a fanatical traveler. She also owns and operates a small travel agency.