H. compressus is the type species of the genus Hyphessobrycon but is not well-known in the ornamental trade.

Hyphessobrycon was raised by Durbin in Eigenmann (1908) as a subgenus of Hemigrammus, differing from the latter by the absence of scales on the caudal-fin.

This species has been recorded from the Guaporé, Madeira, Branco, Trombetas, and Urubu river systems within the Amazon river basin, Brazil.

Type locality is ‘Igarapé Jatuarana, 5 kilometers above Samuel, Rio Guaporé, Rondonia, Brazil’.

Widely-distributed throughout the Amazon, Orinoco, Essequibo, and Tocantins river systems in Brazil, Peru, Bolivia, Ecuador, Colombia, Venezuela, and Guyana.

Type locality is ‘Rio Cupai [= Rio Cupari], Rio Tapajós basin, Amazon River drainage, Pará State, Brazil’.

This species is known from the rio Negro within the Brazilan Amazon basin and upper Río Orinoco system in Venezuela.

Type locality is ‘Rio Adujá, Rio Itú, tributary of middle Rio Negro, Amazonia, Brazil’.

I. geisleri is typically exported for the aquarium trade alongside the similar-looking congener I. adujai (Géry, 1970) but can be identified by presence (vs. absence in I. adujai) of a black lateral stripe on the body beneath the red stripe, and possession of 20-25 (vs. 28-34) anal-fin rays.

H. eschwartzae is told apart from other laterally-striped Hyphessobrycon species from the Madre de Dios watershed by the following characters: 4 simple anal-fin rays (vs. 3 in other species listed); 13-15 dentary teeth (vs. 5-11); 6 teeth in the internal premaxillary ro…

This species superficially resembles the popular silver-tipped tetra, Hasemania nana, but can easily be told apart by presence (vs. absence) of an adipose-fin.

It can be told apart from other Hyphessobrycon sp…

H. borealis is a member of the putative ‘H. heterorhabdus-group’ of closely-related species within the genus as proposed by Géry (1977).

There are around 15 members characterised by a ‘longitudinal pattern’ consisting of a thin, usu…

The two ponds where H. auca was collected were located on a sand bar deposited by the nearby Paraná river during the Pleistocene.

At time of collection the substrates were composed of sand with submerged vegetation dominated by Egeria najas plus floating Eichhornia in marginal areas.

This species is relatively rare in the aquarium hobby but is occasionally traded as ‘red-tailed flag tetra’.

It lends its name to the H. aghula group of closely-related species within the genus as proposed by Géry (1977, see below) of which members share the following characters which set them apart from other characids: lower half of the body dark, especially above the anal-fin; usually possessing a laterally-elongate humeral spot, more-or-less united wit…