Ever since the 19th century, ethnologists and biologists have recorded many reports from the Amazon basin of the grisly habits of the candiru fish. This near-transparent member of the catfish family is said to be capable of swimming up the stream of a man’s urine and lodging itself in the urethra, using sharp barbs that make removal without surgery impossible, before proceeding to devour the human penis.
Also known as the toothpick fish, canero (in Peru), or the even more graphic (and actually far more accurate) “vampire fish”, the candiru (Vandellia cirrhosa) is a parasitic catfish, known to inhabit the waterways of rainforests in Peru, Ecuador, Colombia, Bolivia and Brazil. While some candiru (there are three known species) can grow to around 40 centimeters in length, Vandellia cirrhosa is much smaller, and it is this smaller fish which has earned the fearsome reputation of invading the human urethra.
In fact, while reports have circulated for almost two hundred years concerning the alleged ability of the candiru to lodge itself in male or female human genitalia, the first reported case of one being removed from a human penis dates from 1997, in Brazil, and the veracity of that claim has since been disputed. We owe the first published account of candiru attacks on humans to the 19th century German botanist Carl Friedrich Philipp von Martius, who traveled in South America from 1817 to 1820; however, this intrepid explorer never saw the fish, instead basing his article on the stories he was told by indigenous people in the areas he visited.
While native women do not bathe in rivers while menstruating, for fear that the candiru will be attracted by their blood, the cases of maiming which have undoubtedly occurred among both male and female riverbank dwelling peoples and travelers in the rainforests of South America are more likely to have been the result of a bite from a piranha, a fish with its own terrifying reputation attributable more to Hollywood movie exaggeration than to real-life documented behavior.
Beyond the myth, what is known about the candiru is that it is a parasitic fish with a thirst for blood. The species Vandellia cirrhosa tends to grow to around 5 centimeters in length and lives by entering the gills of larger fish, which it proceeds to parasitize. Backward pointing spines on the candiru’s head allow it to lodge itself in place, enabling it to proceed with its aim of feeding upon the blood of the unfortunate host fish. In the turbid waters of the Amazon and its tributaries, including the Tambopata River, the rather small and near-translucent candiru is very difficult to spot, much less distinguish from dozens of other similar species, even when its head and body are distended after it has gorged itself on its preferred blood meal.