This species is not often available and is much sought after in the aquarium hobby where it’s been traded as ‘crystal rainbow tetra’ and ‘orange-tailed glass tetra’.

It’s also been referred to as a Heterocharax or Tyttocharax species in the past.

It’s currently the only member of its genus which is separated fr…

Known only from the rio Uaupés system in Brazil with type locality ‘brook emptying into Igarape Yavuari River, tributary of River Uaupés, upper Negro River basin, 0°14’31″N, 68°03’48″W, Amazonas, Brazil’.

The full extent of its range is unclear but additional populations may exist.

This is the smallest of three similar-looking species most commonly-referred to as the ‘bleeding heart’ subgroup, the other two being H. erythrostigma and H. socolofi.

All possess a reddish humeral spot which is not present in any other characid with other shared characters including possession of 6 -14 maxillary teeth, 7-9 scales above the lateral line, 5-7 scales below the lateral line and 26-33 anal fin rays.

This species is available on a relatively regular basis, although it’s sometimes confused with the similar-looking congeners H. loretoensis and H. metae.

It can be identified via the following combination of characters as per Géry (1977): elongate in shape with body depth fitting 3.8-3.9 times in its standard length; caudal peduncle narrow, its depth fitting 1.8 times in its length; head short, interorbital broad, snout short and rounded; dorsal-fin insertion an…

The genus Brachychalcinus currently contains four other species: B. copei (Steindachner 1882) from the rio Madeira and rio Solimões; B. nummus Böhlke 1958 from the Upper Amazon region in Colombia, Ecuador and Peru; B. parnaibae Reis 1989 from the rio Parnaíba basin, and B. retrospina Boulenger 1892 from the Rio Paraguay system.

The group is often referred to collectively as ‘silver dollar tetras’ and tho…

Endemic to pthe upper Amazon basin in Peru, around the city of Iquitos.

Most Astyanax spp. are not popular in the aquarium hobby, though the genus is among the most speciose within the family Characidae. A. kennedyi is no exception; you’ll rarely see it offered for sale but may find the occasional specimen mixed among other species in shipments of wild fishes from Peru.

Most Astyanax spp. are not popular in the aquarium hobby, though the genus is among the most speciose within the family Characidae. A. leopoldi is no exception in that you’ll rarely see it offered for sale but may find the occasional specimen mixed among other species in shipments of wild fishes from Peru.

A. bimaculatus is not a popular aquarium fish but is available on occasion exception, most often as a contaminant among shipments of other species.

It’s identity is also in question to an extent with the name currently applied to what is considered to represent a species complex comprising at least four taxa.

While the surface-dwelling form of this species is fairly unremarkable and rarely-seen in the hobby, the blind form is very popular indeed. The two may have diverged as recently as within the last 10,000 years, with the blind form losing its eyes and much of its pigment. This probably happened because the fish needed better development in other sensory areas. Losing unnecessary and energy-consuming aspects of its physiology allowed it to devote more energy to developments such as increased numbers of taste receptors on the head.

This species is normally referred to as A. paraguayensis, but that name has been considered a synonym of A. nattereri since 2003.

Confusion remains however, as the type locality for the latter is ‘Villa Bella’, now known as Parintins, a settlement on the main Amazon river channel between Manaus and Santarém and many kilometres away from the majority of confirmed localities.