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…

It differs from H. paucilepis by possessing 30-31 scales in the lateral row (vs. 28-29), 3 scales between the lateral line and anal-fin (vs. 4), 10 predorsal scales (vs. 9), ii, 9 dorsal-fin rays (vs. iii, 8), 4 maxillary teeth (vs. 1), and the distance between the dorsal-fi…

Known only from headwaters of the upper Paraná river basin in the Federal District plus the neighbouring state of Goiás, central Brazil.

Type locality is ‘Planaltina, Lagoa Fervedeira, Goiás, Brazil’ with additional records existing mostly from the rio São Bartolomeu including the Bananal, Santa Maria-Torto and Gama tributary systems.

Collected from small streams flowing through savanna grassland containing clear, light brown-coloured water with substrates of sand and gravel and little in the way of submerged or riparian vegetation.

At the type locality pH varied between 5.8 – 6.3, GH and KH were both <1°, conductivity was 9-13 μs and temperature 24.7 – 27.2°C/76.6 – 80.1°F.

This species has been traded as ‘six-eyed tetra’ in reference to its colour pattern comprising two dark spots on each flank plus the eye.

Based on the extensive review of the genus by Lucena and Malabarba (2010), in which nine new species were described, P. tegatus can be told apart from congeners by the following combination of characters: lateral line incomplete with 8-13 perforated scales; laterally elongate humera…

Gasteropelecids are commonly-referred to as ‘freshwater hatchetfishes’ due to their heavily-keeled body shape which has evolved in such a way due to possessing an enlarged, heavily-muscled pectoral girdle, and which resembles the shape of a hatchet head.

They are sometimes said to be capable of propelled flight above the water surface by beating their pectoral fins but in fact this is not the case and was disproven by Wiest (1995) who used…

C. carsevennensis has formerly been synonymised with C. arnoldi but was considered separate by Zarske (2011) using the following combination characters: absence (vs. presence) of a silvery-white to white patch in the centre of some of the flank scales in males, particularly in the lower half of the body; absence (vs. presence) of a horizontal dark body bar in nuptial males; absence (vs. presence) of thin black margins in the dorsal, ventral and anal fins; eggs deposited among submerged vegetation (vs. eg…