Hyphessobrycon is a genus of freshwater fish in the characin family (family Characidae) of order Characiformes. The Hyphessobrycon species are among the fishes known as tetras. All species of this genus are native to the Neotropic ecozone in South America.
This large genus of characins includes over 100 species. The systematics of Hyphessobrycon
is still largely unresolved. Six groups within this genus have been recognized based on color patterns alone. With no phylogenetic
analysis of this genus, species are placed into this genus as anatomically defined by Carl H. Eigenmann
in 1917. By this definition, Hyphessobrycon
is identified by the presence of an adipose fin
, incomplete lateral line
, two tooth series in the premaxilla
, with the teeth of the external series continuous in a single series, teeth not strictly conical, preventral scales arranged in more than one row, and lack of scales in the caudal fin
. The characteristic of extension of scales onto the caudal fin that differentiates this genus from Hemigrammus
is not satisfactory as it occurs in intermediate conditions.
This genus is not monophyletic. A monophyletic group within Hyphessobrycon has been hypothesized, termed the rosy tetra clade; this group is based upon coloration pattern and the shape of dorsal and anal fins of males. Recognition of monophyletic groups among Hyphessobrycon species is complicated by the difficulty in finding characters useful for hypothesis of relationships among the species. Traditional characters used to identify Hyphessobrycon are phylogenetically unreliable.
The type species is H. compressus, the Mayan tetra. The generic name, Hyphessobrycon, is of slightly uncertain origin. The second part derives from the Greek βρύκω (to bite); the first, derives from an ostensible Greek hyphesson, which may be an error for υπελάσσων (slightly smaller).
The genus is distributed from southern Mexico
to Río de La Plata
, achieving its highest diversity in Cisandean
northern South America
Appearance and anatomy
All small fishes, the Hyphessobrycon tetras reach maximum overall lengths of about 2–7 cm (0.75–2.75 in). There is great anatomical diversity in this genus. They are generally of typical characin shape, but vary greatly in coloration and body form, many species having distinctive black, red, or yellow markings on their bodies or fins.
species are generally omnivorous
, feeding predominantly on small crustaceans
worms, and zooplankton
. When spawning, they scatter their eggs and guard neither eggs nor young.
Relationship to humans
None of the roughly one hundred fishes in the genus appears on the IUCN Red List
of threatened species. Many Hyphessobrycon
species are popular aquarium
Species list according to the Integrated Taxonomic Information System
, with notes for newer species. New species continue to be described.