Meet The Candiru – The Penis Probing Fish Of Your Nightmares

Published February 15, 2018

The candiru is a tiny, but fearsome, beast that lives in the rivers of the Amazon, and has a penchant for swimming into the human penis.

Vandella Cirrhosa Candiru

Wikimedia Commons
The candiru fish, in an 1856 drawing.

Of all of the beasts that prowl the Amazon, none is more feared by the locals than the candiru. A river monster feared even above the dreaded piranha; the candiru waits for its unsuspecting prey to step into the river before latching onto it.

It’s also only about an inch and a half long, though don’t mistake its small size for weakness. This little fishy packs a punch.

Described as “very small, but uniquely occupied in doing evil,” the candiru favors a more stealthy approach than its flesh-eating counterpart. Rather than go for an outward attack, the candiru implants itself inside the human body through a rather unusual entryway – the human penis.

The fish swims up the penis into the urethra – upstream, which is an impressive feat for such a small fish – where it latches onto the walls with barbs. Removal can be very difficult, as the barbs face one direction only, and pulling on the fish only causes them to sink deeper into the walls of the urethra.

Even more frightening than the prospect of a tiny fish making your penis its home, is the prospect of getting it out. A few native people suggest home remedies like a hot bath or an herbal soak, but for the most part, the verdict is a unanimous and horrifying one: complete removal of the “offending appendage” altogether.

Candirus, a form of Amazonian catfish, were first documented in 1829 when German biologist C.F.P. von Martius was told of them by native Amazon people. They described wearing special urethra covers made of coconut shells, or sometimes simply tying a ligature around their penises while going in or near the water.

Live Candiru

YouTubeA live candiru fish.

A few years later, in 1855, a French naturalist named Francis de Castelnau was told by an Araguay fisherman not to urinate in the river, as it encourages the fish to swim up your urethra.

Over the years, the legend of the candiru’s attacks has not changed at all, save for a few variations regarding what it does once inside the penis. The Amazon people still live in fear of the tiny creature and will go to great lengths to avoid being a victim to the unwelcome intruder. George Albert Boulenger, the curator of Fishes at the British Museum outlined an impressive system of bathhouses, put together by the natives, that allowed them to bathe without ever fully entering the river.

Despite the ever-present fear, the dramatic warnings by natives and the insistence of the candiru’s predatory prowess, only a few documented cases of a candiru parasitic infestation exist.

The only documented modern case took place in 1997, in Itacoatiara, Brazil. The patient, a 23-year-old man, claimed that while he was urinating in a river a candiru jumped from the water into his urethra. He needed a two-hour urological procedure to remove the fish.

Ironically, the only other cases that were documented happened in the 1800s, and to women, not men.

Due to the mysterious nature of the candiru and the fact that no one has seen an attack in action, several marine biologists have claimed that it is nothing more than a legend. They point out the fish’s small stature, and relative lack of self-propulsion as a reason why the fish could never hope to swim up a urine stream. They also point out that the opening to a urethra is tiny, and even a miniscule fish would have to try very hard to make it through one.

The Amazon people remain unconvinced, however, and maintain that the candiru is not to be thought lightly of. Just because no one’s seen one in action doesnt mean that they arent there, waiting for their next unsuspecting victim.


Next, check out the weirdest freshwater fish ever caught. Then, take a look at these seven insects guarenteed to give you nightmares.

Katie Serena
Katie Serena is a New York City-based writer and a staff writer at All That's Interesting.
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