Cetopsis candiru

They are known by multiple names across their range. In Bolivia they are called "Canero" or just "Candiru". The term "Canero" is also used in Peru. Candiru açú is also used on occasion, however according to some researchers this name is primarily used for other species of the genus Cetopsis including C. coecutiens and C. gobioides. Alternatively the name "candiru cobra" is also used. The name Candiru is shared with many other species of catfish, including Vandellia cirrhosa, a parasitic catfish from the family Trichomycteridae which is otherwise unrelated to members of the Cetopsidae. ==Description==

Cetopsis candiru closely resembles its sister species, C. coecutiens, but it may be distinguished through its relatively "shallow" body (body depth 20% of standard length or less) and more incisiform teeth. The dorsal fin is relatively small and located towards the front of the body, lacking spines. The base of the caudal fin (caudal peduncle) is approximately as deep as it is long. The caudal fin itself is symmetrical and slightly forked, with the rounded lobes approximately 1.5 to 1.6 times longer than the shallowest part of the fin. The anal fin is located in the back half of the body and its base takes up approximately a third of the animal's length. Its shape is gently convex and its rear end does not attach to the body. In Cetopsis candiru the pelvic fins are short and paddle-like with rounded symmetrical edges. Like with the anal fin, there is no membrane attaching the last fin ray directly to the body. Finally the pectoral fins are around half as long as the head with rounded edges. Mature males however differ from females and juveniles in the morphology of some of their fins. The first fin rays of both the dorsal and pectoral fins are distinctly elongated beyond what can be seen in younger or female individuals and the anal fin is noticeably more convex. When this sexual dimorphism sets in is not fully known. The smallest specimen showing all of these traits measured in standard length (tip of the skull to the end of the hypural plate). Another, smaller individual measuring shows the onsets of these elements' growth. Alongside C. coecutiens, C. candiru is one of the largest species within the genus Cetopsis. They range in size from to . ==Ecology==

Cetopsis candiru is a carnivorous fish and commonly described as a voracious feeder, making use of powerful jaw musculature and a nearly continuous cutting surface of the incisiform dentition. Their distribution overlaps with that of the related Cetopsis coecutiens and both species are known to simultaneously feed on the same bodies. They do however differ in the specifics of their behavior. Cetopsis candiru typically bite into carcasses and twist to create an entry into the body before proceeding to feed from the inside, where they may congregate in vast numbers during feeding frenzies. Due to these habits carcasses that were fed on by C. candiru oftentimes appear almost entirely skeletonized, but retain cartilage, eyeballs and tight skin. Cetopsis coecutiens on the other hand does not remain inside the body and instead will return to it multiple times, each time ripping away chunks of flesh. Both species leave similar circular bitemarks on bodies they scavenged on. They are opportunistic animals, feeding on the carcasses of animals that have drowned or otherwise died and fallen into the water. The role of these fish as important aquatic scavengers is highlighted by their prominent appearance in forensics around the Amazon, being well known to even feed on dead human bodies found in the various rivers of northern South America. At least one confirmed report tells of a single Cetopsis attacking a living child, although the exact culprit could not be determined between the two carnivorous species C. candiru and C. coecutiens. Other reports mention Cetopsis candiru feeding on live fish caught in gillnets or hooked by fishermen. ==Distribution==

Cetopsis candiru is known across large parts of the Amazon Basin. Specimens have been discovered in Brazil close to the Amazon River itself, the Rio Tocantins, the Rio Negro, the Rio Purus and the Rio Madeira among others. In Bolivia they occur in various tributaries to the Rio Madeira such as the Rio Beni and in Peru they were recovered from the Rio Ucayali and other tributaries to the Amazon. Some scientists also report the presence of Cetopsis candiru from eastern Ecuador. ==Taxonomy and classification==

Cetopsis candiru was first described in 1829 by Spix & Agassiz on the basis of four syntype specimens. The same year Cuvier established the name Silurus candira, which however is a nomen nudum. Several other names were subsequently coined, none of which however remained. In 1839 Cetopsis spixii was introduced in an attempt to replace the prior name and in 1862 C. candiru was chosen to serve as the type species of the newly erected genus Hemicetopsis. Several synonyms are also the result of authors variously using either "candiru" or "candira" as the species name. }} ==References==