Vandellia cirrhosa, known by the common names candiru, 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 name "candiru" is also used to refer to other catfish species, including the entire genus Vandellia.
This species is known for an alleged tendency to invade and parasitize the human urethra and other bodily openings; 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. Scientifically, this fish only parasitizes larger fish which it shares its habitat with; it consumes their host's blood from their gill openings, thus the candiru is a hematophagic species.
Discovery
Vandellia cirrhosa was discovered in the early 1800s by Alexandre Rodrigues Ferreira, a Native Brazilian scholar studying under the Italian naturalist Professor Domingos Vandelli, of which the fish would be named after. The Spanish name cañero is a derivative of carnero, meaning flesh-eater.
Taxonomy
Candiru belong to the family Trichomycteridae, which is monophyletic and contains 207 species. The taxonomic placement of this fish has long been debated, with the first proposed phylogenetic relationships of Trichomycteridae being proposed by Jonathan N. Baskin in 1973. Most proposed phylogenies have relied on morphological data, often placing Vandellinae and Stegophilinae as sister taxa among the subfamilies. A study conducted by Luis Fernández and Scott A. Schaefer, published in 2009, used DNA sequence data to create the first comprehensive treatment of phylogenetic relationships of trichomycterid catfish. Relationships among Vandelliinae were strongly supported, and Vandellia was found to be the sister group of Plectrochilus. The results of Fernández and Schaefer were fully congruent with previous statements based on morphological data.
Description
thumb|An artistic rendition of Vandellia cirrhosa.
Vandellia cirrhosa is a small, freshwater catfish. Members of the genus Vandellia can reach up to in standard length, but some others can grow to around . The fish has an elongated body with an anterior dorsal fin and pelvic fin, and an anal fin slightly larger than the dorsal fin. The caudal fin is fairly small with a truncated shape. 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. Blood is often visible through the translucent body after feeding. The fish has small eyes with yellow irises. There are short sensory barbels around the head, together with short, backward pointing spines on the gill covers. These spines have been described as popping out in an umbrella-like fashion, which could be used to help lodge the fish into its host. Their bodies are very small and elongated to easily slip into the gills of host fish.
Habitat and distribution
Candiru inhabits the Amazon and Orinoco basins of lowland Amazonia.
This fish lives in shallow water with muddy, sandy, or rocky bottoms. It can be found in riffles. Its distribution is patchy and it does not seem to move very far from its spawning sites.
Diet
thumb|right|A candiru taking blood from the gills of a fish host.
thumb|A closeup of a feeding candiru as it begins to swell with blood.
Candiru are hematophagous and parasitizes the gills of larger Amazonian fish, especially catfish of the family Pimelodidae (Siluriformes) and members of the family Characidae.
The feeding mechanism of the candiru was not understood until fairly recently, but many theories had been proposed before. Some suggested that it uses its sharp teeth to latch onto an artery or vein and stays attached to the host until it has ingested enough blood. It then lets go of the host and continues swimming.