Vandellia cirrhosa, AKA Candiru   


(Description is from (Link is no longer active.)

I have heard about a tropical fish which can detect traces of mammalian urine in the water and will enter the urinary tract of the mammal. Is this true? What is it's taxonomy etc.?

The fish you are referring to is the Vandellia cirrhosa, common name candiru, a member of the family Trichomycteridae the pencil or parasitic catfishes.

Vandellia is about an inch (2.5 cm) in length and when it has not fed is slender and almost transparent (except for the eyes). It lives in the rivers of tropical South America.This small catfish is a vampire - it feeds on the blood of other fish.

It has been described as entering the gill chambers of larger fish to suck blood from their gills. Once in the gill chamber it anchors itself there, so as not to be flushed out as the fish pumps water over its gills, with spines on its gill covers. As it feeds the body becomes engorged and distended with blood. Once it has fed the candiru swims out of the gill chamber and burrows into the river-bed to digest its blood meal.

You are correct in believing that the candiru poses a hazard to humans (and other mammals that might urinate in the water). It seems attracted to the flow of urine (possibly as it resembles the stream of water from the gills of a large fish). The candiru may swim up the stream of urine and enter the urethra of a bather urinating into the river.

This, of course, not part of the fish's normal feeding behaviour - the fish has made a fatal mistake. Once up the urethra the fish can not turn nor can it move backwards because of the rear-pointing spines on its gill covers. It is locked in. The fish invariably dies and the dead fish and associated swelling of the lining of the urethra cause the urethra to become blocked. Surgery is required to remove the obstruction.

Some recent expeditions to the Amazon region have had their personnel wear cricket box type shields to protect against candiru whilst swimming in or wading through streams. Authorities in the USA are concerned that candiru might possibly escape from aquaria and populate the rivers of the southern US. For this reason the importation into parts of the USA of any member of the family Trichomycteridae is strictly prohibited.

MAN, one of these things inside your urethra could REALLY spoil your day, y'know??


 P.S. I don't care HOW FULL your bladder is, do not EVER, EVER pee into the Amazon River!!


Dr Anuar Samad removed a Candirú from a man in 1997. Photo: Anuar Samad.



Candirú. From Wikipedia

This is a catfish, Vandellia cirrhosa, which is found in the Amazon. It can enter the urinary tract of human beings and suck blood. This is said to be immensely painful. If you swim naked and urinate in the water the candirú can find its way in.

The fish is transparent, and virtually invisible in the water. It is not rare, although attacks on humans are. There is only one recent report of a man being invaded by a candirú, published in Portugese:
Anuar Samad: Incrível causa de Uretrorragia! Arquivos Ellis 2004 1:2; 13. Normally these fish survive by sucking blood from the gills of larger fisher. Their fame can be attributed to the fact that they are what the media call "sexy news".

When swinning in the Essequibo river I was careful to always use a swimming suit, in fear of candirú. I also did not want one of the many piranhas found there to take a chunk out of me.




When the candiru strikes, you’ll know it…