Candiru

The candirú or canero (Vandellia cirrhosa) is a freshwater fish in the group commonly called the catfishes. It is found in the Amazon River and has a reputation among the natives as the most feared fish in its waters, even over the piranha[?]. The species grows only to a size of an inch in length and is eel shaped and translucent, making it almost impossible to see in the water. The candiru is a parasite. It swims into the gill cavities of other fishes, erects a spine to hold it in place, and feeds on the blood in the gills, earning it a nickname as the "vampire fish of Brazil".

It is feared by the natives because it is attracted to urine or blood, and if the bather is nude it will swim into an orifice (the anus, vagina or even - in the case of the smaller specimens - the penis). It then erects its spine and begins to feed on the blood and body tissue just as it would from the gills of a fish. The candiru is then almost impossible to remove except through an operation, usually involving the amputation of the area. A more expensive option is the use of two plants, the Xagua plant (Genipa americana) and the Buitach apple which are inserted (or their extract in the case of tight spaces) into the affected area. These two plants together will kill and then dissolve the fish. More often, the pain causes shock and death in the victim before it can be removed.