---
title: "What the sources say about the Candiru | AnimalTracks.wiki"
description: "40 claims from the Candiru profile, each beside the words of the source that backs it."
image: "https://animaltracks.wiki/images/animals/candiru-1.webp"
canonical: "https://animaltracks.wiki/animals/candiru/sources/"
---

# What the sources say about the Candiru (*Vandellia cirrhosa*)

> 40 claims from the Candiru profile, each beside the words of the source that backs it. A "..." marks a cut in a quote and [brackets] an insertion.

Profile: [Candiru](https://animaltracks.wiki/animals/candiru/)

## Haddad Junior, Zuanon & Sazima (2021). Medical importance of candiru catfishes in Brazil: A brief essay. Revista da Sociedade Brasileira de Medicina Tropical.

https://doi.org/10.1590/0037-8682-0540-2020

| The page says | The source says |
| :--- | :--- |
| The urethra legend says a candiru will swim into the human urethra to feed on blood. | they allegedly enter the human urethra or other natural orifices to feed on blood |
| They also say there is no robust evidence that candirus in the group that includes Vandellia react to ammonia or blood in water. | There is no robust evidence that vandelliine candirus react to ammonia or blood in water |
| Haddad Junior and colleagues call those cases disputed, given the apparent lack of solid evidence. | such cases are disputed due to the apparent lack of solid evidence |
| Stories say they do, but researchers who examined the published accounts call such cases disputed, given the apparent lack of solid evidence. | We examined published accounts ... they allegedly enter the human urethra or other natural orifices to feed on blood ... such cases are disputed due to the apparent lack of solid evidence |
| They also warn that reports on candirus and human health are biased by second- and third-hand accounts, misconceptions and folk tales. | reports on candirus and their relationship to human health and death are biased by imprecision, second- and third-hand accounts, misconceptions, and folk tales |

## Brejão (2023). Vandellia cirrhosa. The IUCN Red List of Threatened Species 2023: e.T49830470A160427716.

https://doi.org/10.2305/iucn.uk.2023-1.rlts.t49830470a160427716.en

| The page says | The source says |
| :--- | :--- |
| Least Concern | IUCN Red List category: Least Concern (LC). |

## Vandellia cirrhosa (Candiru). Animal Diversity Web, University of Michigan.

https://animaldiversity.org/accounts/Vandellia_cirrhosa/

| The page says | The source says |
| :--- | :--- |
| Let the Host Do the Work | Candiru are parasites, feeding on the blood of other fish. |
| The candiru (Vandellia cirrhosa) is a parasite: an animal that feeds on another animal in a harmful way without killing it right away. | an organism that obtains nutrients from other organisms in a harmful way that doesn't cause immediate death |
| Its meal is the blood of other fish. | Candiru are parasites, feeding on the blood of other fish. |
| Once it finds a host, it heads for the gills. It either forces itself under the gill cover (the operculum) or waits for the cover to open on its own. | 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. |
| Then it latches onto an artery. | Once past the operculum, these parasites latch onto the ventral or dorsal aortal arteries. |
| The host's blood pressure pumps blood straight into the candiru's mouth. | The host's blood pressure pumps blood straight into the candiru's mouth; these parasites do not "suck" blood |
| The candiru does not suck. | these parasites do not "suck" blood |
| A meal usually lasts 30 to 145 seconds, and then the candiru sinks and burrows into the river bottom. | The length of a single blood meal is usually short, from 30-145 seconds. After feeding, candiru sink and burrow into the river bottom. |
| One idea is that it follows the scent of ammonia and other waste from possible hosts, but that has not been proven. | It is hypothesized that candiru track the scent of ammonia and other excretions from potential prey, although this has not been definitively proven. (note: Final pass: replaced 'likely uses a mix of chemical and visual cues'. ADW's chemical cue rests on this ammonia hypothesis, and Haddad 2021 (current) finds no robust evidence vandelliines react to ammonia, so the page states the hypothesis as unproven.) |
| Its eyes are large, but it usually lives in cloudy water, so eyesight is probably not its main way to find one. | 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. |
| Tiny and See-Through | Candiru are small, thin catfish. They have no scales and their bodies are transluscent |
| A candiru grows to 17 centimeters (6.7 inches) at most, and most are much smaller. | Maximum total length for this species is 17 cm, though most specimens are much smaller. ... 6.69 (high) in (note: 6.7 in rounds the source's 6.69 in) |
| The average is 5 centimeters (about 2 inches). | Average length 5 cm 1.97 in (note: about 2 in rounds 1.97 in) |
| It has no scales, and its body is translucent, gaining color only after it feeds. | They have no scales and their bodies are transluscent, becoming colored only after feeding. |
| Its mouth is lined with tiny needle-like teeth, and its large black eyes sit on top of its head. | barbels near their mouths, which are lined with minute, needle-like teeth |
| its large black eyes sit on top of its head | large black eyes (relative to body size), which are placed on top of the head |
| Short spines on its gill covers face backward. They help keep it from being dislodged while it feeds. | Candiru have short, backward facing spines on their gill covers, which help to prevent it from being dislodged while feeding |
| Candiru live in the upper Amazon and Orinoco river basins of northern South America. | Candiru are found exclusively in the upper Amazon River and Orinoco River basins in northern South America. |
| They live in shallow, slow-moving, acidic water with muddy or sandy bottoms. | Candiru live in shallow, slow moving, acidic waterways with muddy or sandy bottoms. |
| They are found burrowed into the riverbed most of the time, coming out only to feed or mate | These demersal fish can be found burrowed in the riverbed most of the time, only emerging to feed or mate. |
| and they feed by day as well as at night. | they actively feed during the day as well as at night. |
| Their hosts include the tambaqui, the golden dorado and the red-bellied piranha. | Tambaqui ( Colossoma macropomum ) Amazonian pacu ( Piaractus brachypomus ) Red-bellied piranha ( Pygocentrus nattereri ) Golden dorado ( Salminus maxillosus ) |
| Tambaqui have been seen fighting back by tightening their gill covers and sweeping the parasites away with their fins. | have been observed to exhibit defense mechanisms against candiru attacks, such as tightening their operculum and using their fins to sweep the parasites away. |
| Candiru very rarely kill a host, and hosts usually heal quickly after an attack. | They very rarely kill their hosts, who usually heal quickly after an attack. |
| The translucent, thin catfish that slips under a fish's gill cover and lets the host's own blood pressure fill its mouth. | it either forces itself under the operculum or waits for it to open naturally. ... The host's blood pressure pumps blood straight into the candiru's mouth |
| Shallow, slow-moving waterways with muddy or sandy bottoms in the upper Amazon and Orinoco basins | Candiru are found exclusively in the upper Amazon River and Orinoco River basins in northern South America. ... Candiru live in shallow, slow moving, acidic waterways with muddy or sandy bottoms. |
| Blood of other fish, taken from arteries at the gills | Candiru are parasites, feeding on the blood of other fish. ... it heads towards the gills ... Once past the operculum, these parasites latch onto the ventral or dorsal aortal arteries. |
| Gill-cover spines that hold it on while its host's blood pressure fills its mouth | 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 |
| Animal Diversity Web notes that these parasites do not suck blood, as people once thought. | these parasites do not "suck" blood as has been previously hypothesized |
| The host fish's own blood pressure does the pumping, and spines on the candiru's gill covers help it stay attached. | 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 |
| A candiru tops out at 17 centimeters (6.7 inches), but most are much smaller, and the average length is 5 centimeters (about 2 inches). | Maximum total length for this species is 17 cm, though most specimens are much smaller. ... Range length 17 (high) cm 6.69 (high) in Average length 5 cm 1.97 in (note: 6.7 in and 2 in are roundings of the source's 6.69 and 1.97 in) |
| a translucent catfish that stays burrowed in the riverbed and emerges only to feed | These demersal fish can be found burrowed in the riverbed most of the time, only emerging to feed or mate. (note: Task #974: vibe.reason re-anchored on the burrow-and-feed cycle.) |
| on a blood meal that usually lasts 30 to 145 seconds before it sinks back into the mud | The length of a single blood meal is usually short, from 30-145 seconds. After feeding, candiru sink and burrow into the river bottom. |
| dangerLevel: Medium | It is possible for candiru to parasitize humans, though this is very rare. (note: Task #974: Medium ('Can injure, but rarely seriously'), not Low: ADW lists 'injures humans' under negative impacts. Haddad 2021 calls the urethra cases disputed, so nothing supports a higher tier.) |