The payara, ''Hydrolycus scomberoides'', is a

species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...

of dogtooth tetra. This predatory fish is found in the

Amazon Basin The Amazon basin is the part of South America drained by the Amazon River and its tributaries. The Amazon drainage basin covers an area of about , or about 35.5 percent of the South American continent. It is located in the countries of Bolivi ...

in tropical South America.SeriouslyFish:
Hydrolycus scomberoides.
' Retrieved 31 October 2015. It was the first of four species to be described in the

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...

'' Hydrolycus''.

Description

The most noticeable feature of ''H. scomberoides'' is the two long fangs protruding from its lower jaw. These are used to impale their prey, mostly smaller fish. It typically reaches a

standard length Fish measurement is the measuring of individual fish and various parts of their anatomies. These data are used in many areas of ichthyology, including taxonomy and fisheries biology. Overall length * Standard length (SL) is the length of a fish m ...

of about , but can reach up to . There are reports of far larger individuals, up to in total length and in weight, based on records by IGFA, but this likely involves confusion with the related '' H. armatus''. ''H. scomberoides'' is overall silvery with a dark spot behind the

opercle The operculum is a series of bones found in bony fish and chimaeras that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. Anatomy The opercular series contains four bon ...

and another at the lower base of the

pectoral fin Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as ...

. In adults the tail is dusky on the basal half, turning paler (more transparent) towards the tip.

In the aquarium

The payara, which is also sold as the saber tooth barracuda, vampire fish, vampire tetra, or saber tusk barracuda, is a popular species for large, aggressive aquariums. It requires a large aquarium and can only be mixed with relatively large species, as smaller will be seen as potential prey.

References

{{Taxonbar, from=Q737277 Cynodontidae Sport fish Fish of the Amazon basin Freshwater fish of Brazil Freshwater fish of Colombia Fish described in 1819 Taxa named by Georges Cuvier