Numbers of candiru are unknown, but there are no conservation efforts to evaluate or maintain current population levels.
US Federal List: no special status
CITES: no special status
State of Michigan List: no special status
Although there are no reports of candiru predators, it is very likely that larger carnivorous fish may feed on them.
Candiru are small, thin catfish. They have no scales and their bodies are transluscent, becoming colored only after feeding. These fish have barbels near their mouths, which are lined with minute, needle-like teeth. Maximum total length for this species is 17 cm, though most specimens are much smaller. The body is narrow and cylindrical, with a slightly flattened head. Candiru have short, backward facing spines on their gill covers, which help to prevent it from being dislodged while feeding, and large black eyes (relative to body size), which are placed on top of the head.
Range length: 17 (high) cm.
Average length: 5 cm.
Other Physical Features: ectothermic ; bilateral symmetry
There is no information available regarding the lifespan of candiru, either in captivity or in the wild.
Candiru live in shallow, slow moving, acidic waterways with muddy or sandy bottoms. These demersal fish can be found burrowed in the riverbed most of the time, only emerging to feed or mate.
Habitat Regions: tropical ; freshwater
Aquatic Biomes: benthic ; rivers and streams
Candiru are found exclusively in the upper Amazon River and Orinoco River basins in northern South America.
Biogeographic Regions: neotropical (Native )
Candiru are parasites, feeding on the blood of other fish. When a candiru locates a host (through visual and chemical cues), it heads towards the gills, where it either forces itself under the operculum or waits for it to open naturally. Once past the operculum, these parasites latch onto the ventral or dorsal aortal arteries. Opercular spines help candiru stay attached to hosts' gills and aid in releasing blood. The host's blood pressure pumps blood straight into the candiru's mouth; these parasites do not "suck" blood as has been previously hypothesized. The length of a single blood meal is usually short, from 30-145 seconds. After feeding, candiru sink and burrow into the river bottom. Other species of larger catfish (Brachyplatystoma vaillantii, Pseudoplatystoma sp.) and characins (Piaractus brachypomus, Pygocentrus nattereri, Salminus brasiliensis, Colossoma macropomum, Brycon spp.) are also known to be hosts for candiru. Colossoma macropomum have been observed to exhibit defense mechanisms against candiru attacks, such as tightening their operculum and using their fins to sweep the parasites away.
Animal Foods: fish; blood
Primary Diet: carnivore (Sanguivore )
Candiru are parasites of many species of fishes. They very rarely kill their hosts, who usually heal quickly after an attack.
Ecosystem Impact: parasite
Species Used as Host:
There are no known positive effects of candiru to humans outside of scientific research.
Positive Impacts: research and education
It is possible for candiru to parasitize humans, though this is very rare. There have been reports of Candiru swimming up the urethra of men and women who urinate while in the water. It is believed that attacks are accidental, as they die once inside the urethra. Although there are many stories published, it is difficult to assess their accuracy and validity, as candiru are only found in a region where scientific researchers and qualified doctors are not always available.
Negative Impacts: injures humans (bites or stings)
There is currently no information available regarding development in this species. Generally speaking, catfish eggs are spherical in shape and are externally fertilized. Once sperm enters an egg, cell cleavage begins and the embryo starts to develop. Gestation time is unknown for this species. Young hatch with a visible yolk-sac, which acts as a food source during early development and is gradually absorbed, with post-yolk sac individuals resembling small adults.
Candiru likely use a combination of chemical and visual cues to locate hosts. It is hypothesized that candiru track the scent of ammonia and other excretions from potential prey, although this has not been definitively proven. Their eyes are quite large, which may indicate high visual acuity; however, candiru are typically found in turbid water where vision is limited, so eyesight is probably not the primary mode of host detection. Like most fish, candiru have a lateral line system which helps to alert them to movements in the water around them.
Communication Channels: visual ; chemical
Perception Channels: visual ; tactile ; acoustic ; vibrations ; chemical
Mating behaviors of candiru have not been observed in the wild. There is only one recorded instance of these fish spawning in captivity. In this record, a male fish swam around a female, driving her down toward the substrate. Eggs and sperm were released when the fish were in direct lateral contact with each other.
Mating System: polygynandrous (promiscuous)
There is very little information regarding the general reproductive behavior of this species. The only indication of a breeding season is the record of capture of a candiru in late December with ripe ovaries. In captive spawning, 4-5 eggs were released by the female at a time, with breeding taking place multiple times over the span of 3 days. None of the eggs produced were viable, however. There is also currently no information available regarding gestation time or size of young at birth.
Breeding interval: It is assumed that candiru breed multiple times during their breeding season.
Breeding season: Breeding season for this species is unknown but females with ripe ovaries have been collected in December.
Range number of offspring: 4 to 15.
Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (External ); oviparous
There is no information regarding parental investment in this species. In captivity, eggs were laid with no nesting behavior and seemingly with no preference for substrate. Parents did not provide any investment beyond fertilization.
Parental Investment: no parental involvement
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 found in the countries of Bolivia, Brazil, Colombia, Ecuador, and Peru.
The definition of candiru differs between authors. The word has been used to refer to only Vandellia cirrhosa, the entire genus Vandellia, the subfamily Vandelliinae, or even the two subfamilies Vandelliinae and Stegophilinae.[1][2][3][4]
Although some candiru species have been known to grow to a size of 40 centimetres (16 in) in length, others are considerably smaller. These smaller species are known for an alleged tendency to invade and parasitise the human urethra; however, despite ethnological reports dating back to the late 19th century,[5] the first documented case of the removal of a candiru from a human urethra did not occur until 1997, and even that incident has remained a matter of controversy.
Candirus are small fish. Members of the genus Vandellia can reach up to 17 cm (7 in) in standard length,[6] but some others can grow to around 40 cm (16 in). Each has a rather small head and a belly that can appear distended, especially after a large blood meal. The body is translucent, making it quite difficult to spot in the turbid waters of its home. There are short sensory barbels around the head, together with short, backward pointing spines on the gill covers.[7]
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).
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.
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 ligatures around their penises 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.[8] Later experimental evidence has shown this to be false, as the fish actually hunt by sight and have no attraction to urine at all.[9]
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."[10] While Castelnau himself dismissed this claim as "absolutely preposterous," and the fluid mechanics of such a maneuver 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.[11]
In 1836, Eduard Poeppig documented a statement by a local physician in Pará, known only as Dr. Lacerda, who offered an eyewitness account of a case where a candiru had entered a human orifice. However, it was lodged in a native woman's vagina, rather than a male urethra. He relates that the fish was extracted after external and internal application of the juice from a Xagua plant (believed to be a name for Genipa americana). Another account was documented by biologist George A. Boulenger from a Brazilian physician, named Dr. Bach, who had examined a man and several boys whose penises had been amputated. Bach believed this was a remedy performed because of parasitism by candiru, but he was merely speculating as he did not speak his patients' language.[12] American biologist Eugene Willis Gudger noted that the area which the patients were from did not have candiru in its rivers, and suggested the amputations were much more likely the result of having been attacked by piranha.[11]
In 1891, naturalist Paul Le Cointe provides a rare first-hand account of a candiru entering a human body, and like Lacerda's account, it involved the fish being lodged in the vaginal canal, not the urethra. Le Cointe actually removed the fish himself, by pushing it forward to disengage the spines, turning it around and removing it head-first.[13]
Gudger, in 1930, noted there have been several other cases reported wherein the fish entered the vaginal canal, but not a single case of a candiru entering the anus was ever documented. According to Gudger, this lends credence to the unlikelihood of the fish entering the male urethra, based on the comparatively small opening that would accommodate only the most immature members of the species.[11]
To date, there is only one documented case of a candiru entering a human urethra, which took place in Itacoatiara, Brazil, in 1997.[14][15] In this incident, the victim (a 23-year-old man known only as "F.B.C.") claimed a candiru "jumped" from the water into his urethra as he urinated while thigh-deep in a river.[16] After traveling to Manaus on October 28, 1997, the victim underwent a two-hour urological surgery by Dr. Anoar Samad to remove the fish from his body.[15]
In 1999, American marine biologist Stephen Spotte traveled to Brazil to investigate this particular incident in detail. He recounts the events of his investigation in his book Candiru: Life and Legend of the Bloodsucking Catfishes.[17] Spotte met Dr. Samad in person and interviewed him at his practice and home. Samad gave him photos, the original VHS tape of the cystoscopy procedure, and the actual fish's body preserved in formalin as his donation to the INPA.[18] Spotte and his colleague Paulo Petry took these materials and examined them at the INPA, comparing them with Samad's formal paper. While Spotte did not overtly express any conclusions as to the veracity of the incident, he did remark on several observations that were suspicious about the claims of the patient and/or Samad himself.
When subsequently interviewed, Spotte stated that even if a person were to urinate while "submerged in a stream where candiru live", the odds of that person being attacked by candiru are "(a)bout the same as being struck by lightning while simultaneously being eaten by a shark."[23]
In 21st episode of 3rd season of Grey's Anatomy, a man is admitted to a hospital with a candiru fish in his urethra.
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 found in the countries of Bolivia, Brazil, Colombia, Ecuador, and Peru.
The definition of candiru differs between authors. The word has been used to refer to only Vandellia cirrhosa, the entire genus Vandellia, the subfamily Vandelliinae, or even the two subfamilies Vandelliinae and Stegophilinae.
Although some candiru species have been known to grow to a size of 40 centimetres (16 in) in length, others are considerably smaller. These smaller species are known for an alleged tendency to invade and parasitise the human urethra; however, despite ethnological reports dating back to the late 19th century, the first documented case of the removal of a candiru from a human urethra did not occur until 1997, and even that incident has remained a matter of controversy.
