NARRATOR: The animal kingdom has never been short of its myths and legends. Big Foot, the Yeti, and the Loch Ness Monster all inspire our imaginations. The world of parasites also has a legend.
SILVIO BARBOSA: Many people think that it is a legend, but it’s not; it happened to me.
NARRATOR: This is the candiru. It’s a parasitic fish from the Amazon basin in Brazil. It lives off the blood of other fish. This catfish is releasing a trail of urea and ammonia from its gills. The candiru picks up the scent and follows it. Once inside, the parasite uses a set of spines to hook onto the fish and then feeds on its blood. Silvio Barbosa lives on the banks of the Amazon River. That afternoon, he was in the wrong place at the wrong time. One candiru fish was set to make a terrible mistake.
BARBOSA: I felt like urinating. I stood up and it was then it attacked me. The candiru attacked me.
NARRATOR: To the locals living on the Amazon, the candiru fish is legendary. It’s commonly called “the willie fish.”
BARBOSA: When I saw it, I was terrified. I grab it quickly so it wouldn’t go deep inside. I could only see the end of its tail flapping. I tried to grab it but it slipped away from me...
NARRATOR: Silvio’s story is the first ever scientifically proven and documented case of the candiru attacking a human. Doctor Jansen Zuanon is a fish specialist.
DOCTOR JANSEN ZUANON: So we suppose that the candirus are attracted to the humans by the urine or some urea components and even by the movement of the stream of liquid when the people is urinating in the water.
BARBOSA: I was very afraid, because the candiru bites, it eats. When it goes in, it eats everything everywhere. It won’t stop eating, non-stop. This is a fish that eats everything in terms of meat. This is a carnivorous fish.
NARRATOR: Only one doctor was prepared to investigate his claims: A renowned ureogenital surgeon, Doctor Anoar Samad.
DOCTOR ANOAR SAMAD: The legend here, in Brazil, is very famous about the candiru and his capacity to enter in penis, in vagina, and the patient told me that a fish entered his penis.
NARRATOR: Using an endoscope, Doctor Samad could see that the candiru, with its expandable spines, had firmly lodged itself into Silvio’s penis.
SAMAD: I removed the entire fish. It was 6 inch long and about 1/2 inch wide.
BARBOSA: I was surprised because when I saw it I thought it would be smaller, but it was bigger than I imagined. The candiru specimen was sent for identification to the National Institute for Amazonian Research.
ZUANON: After maybe centuries of stories telling about candirus attacking human people, now we have the proof of the fact: A fish that was surgically removed from the patient and positively identified as a candiru. So it's not more a myth or a legend; it's truth.
NARRATOR: Your chances of ever being attacked by a candiru are very slim, but the parasites are out there, living inside more than half the humans on earth.
UNKNOWN SPEAKER: I don’t think human beings will ever be smart enough to eradicate parasites from the human race, and there are many reasons for that. You know, they’re very, very clever. They’ve been at this game much longer than us and if you try and push them on one way, they’ll come up in another way. And for all our wonderful drives and fantastic advances in the last 50 years, there’s no doubt at all that these guys are here to stay.