Candiru (freshwater fish)

1. Candiru, Vandellia cirrhosa, also known as cañero, toothpick fish, or vampire fish, is a species of parasitic freshwater catfish in the family Trichomycteridae native to the Amazon Basin where it is ... Scientific name: Vandellia cirrhosaHigher classification: Vandellia

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4. Description:

The Amazon doesn’t only breed giants, and the small creatures are just as terrifying, at least if you believe the stories that surround them. Candiru are small, parasitic, freshwater catfish famous for launching themselves up the urethra of anyone foolish enough to urinate in the river, and getting lodged into the urinary tract because of the spines that run along their backs. While documented cases are rare, and there is some debate over whether these types of injuries occur at all, there is at least one documented case of a man requiring surgery to remove a candiru from his urethra—which had also attempted to burrow through to his testicles. However, the candiru usually preys on fish, attaching themselves to the larger fish’s gills with their spines and feeding on their host’s blood.

Location and habitat:

Candirus (Vandellia) inhabit the Amazon and Orinoco basins of lowland Amazonia, where they constitute part of the Neotropical fish fauna. Candirus are hematophagous and parasitize the gills of larger Amazonian fishes, especially catfish of the family Pimelodidae (Siluriformes).

A couple interesting facts about the Candiru:

• A transparent catfish: The Candiru is able to sneak up on its hosts by merit of its small size and light-colored, somewhat transparent appearance. Looking more like a fish that resides in caves, the Candiru is very difficult to see in the murky waters of Amazonian rivers.
  
  
• Belongs to a large family of catfish: The Candirus are just three species (one of which occurs in Tambopata) in the large Trichomycteridae family of catfish. Known as the Pencil-Catfish, some of the 207 species live in caves, while others feed on the scales, blood, and even mucous of fish.

Alleged attacks on humans

Although lurid anecdotes of attacks on humans abound, very few cases have been verified, and some alleged traits of the fish have been discredited as myth or superstition.

Historical accounts

The earliest published report of candiru attacking a human host comes from German biologist C. F. P. von Martius in 1829, who never actually observed it, but rather was told about it by the native people of the area, including that men would tie a ligature around their penis while going into the river to prevent this from happening. Other sources also suggest that other tribes in the area used various forms of protective coverings for their genitals while bathing, though it was also suggested that these were to prevent bites from piranha. Martius also speculated that the fish were attracted by the "odor" of urine.^[7] Later experimental evidence showed this to be false, as the fish actually hunt by sight and have no attraction to urine at all.

Another report from French naturalist Francis de Castelnau in 1855 relates an allegation by local Araguay fisherman, saying that it is dangerous to urinate in the river as the fish "springs out of the water and penetrates into the urethra by ascending the length of the liquid column."^[ While Castelnau himself dismissed this claim as "absolutely preposterous," and the fluid mechanics of such a thing occurring defy the laws of physics, it remains one of the more stubborn myths about the candiru. It has been suggested this claim evolved out of the real observation that certain species of fish in the Amazon will gather at the surface near the point where a urine stream enters, having been attracted by the noise and agitation of the water.