Widely-distributed throughout much of the Paraná and Uruguay river systems in Brazil, Paraguay, Argentina and Uruguay.

Some records from Buenos Aires province, Argentina are now considered to refer to the congener H. togoi (Miquelarena and López, 2006) so the common vernacular name ‘Buenos Aires tetra’ may not…

Generally peaceful making it an ideal resident of the well-researched community aquarium.

It is perhaps best-maintained alongside similarly-sized characids, gasteropelecids, lebiasinids, smaller callichthyid or loricariid catfishes and non-predatory, medium-sized cichlids.

Try to buy a mixed-sex group of at least 8-10 specimens, incl…

This species is uncommon in the aquarium trade although its name is sometimes applied to other species.

It was originally described in the monotypic genus Pseudopristella, and can be distinguished from the vaguely similar Pristella maxillaris by possession of a relatively large (vs. relatively small) humeral spot and having black pigmentation in the anal-fin restricted to the first ray (vs. a prominent distal blotch).

P. maxillaris is one of the more popular tetras in the hobby, and is easily obtainable from most aquatic shops. It must rank among the very best choices for the newcomer to fishkeeping as it's peaceful, hardy and inexpensive. There's a selectively-bred "golden" strain available which is actually a semi-albino fish. Care is much the same as for the standard form.

Currently the only species in the genus, in older literature it's often referred to by the now invalid name…

For aquarists perhaps more useful are the subtle differences in colour pattern with P. simulans differing from both P. innesi and P. axelrodi in possessing a greener (vs. bluer) lateral stripe which covers more (vs. less) of the eye/head and extends to the caudal-fin base (vs. terminating anterior to caudal-fin base), a lesser (vs. greater) amount of relatively duller (vs. brighter) red pigmentation on the flanks.

The taxonomic history of all three species is complicated with earlier authors such as Géry (1960, 1977) ten…

Type locality is the Río Calima in Valle del Cauca department, western Colombia.

The Calima is a major tributary within the Río San Juan system and N. lacortei is considered endemic to this drainage.

This species can be found in most dealers' tanks and is one of the best choices for the newcomer to fishkeeping, being attractive, hardy and inexpensive. As virtually all the fish sold in the trade have been captive bred they tend to be relatively unfussy regarding water chemistry and diet.

It's occasionally confused with N. lacortei, which is currently the only other species in the genus. They can easily be told apart by looking at the eye of the fish in question, as the male N. l…

This small species is a popular aquarium fish but there is some confusion surrounding its identity. Two colour forms have been traded, one of which also possesses tiny hooks on the fin rays.

It can be distinguished from congeners by colour pattern; the body is rose-coloured, fins red with no black markings, and the ovoid humeral spot is prominent, measuring around half of the body depth.

At least two colour forms have been traded, one of which is more intensely-coloured and has been referred to as H. sweglesi ‘red’ or ‘rubra’. The bright red pigmentation is retained in long-term captive specimens, suggesting that it is not considered to be an artefact of diet, but we suspect it might reflect conditions at the collection locality with the reddest fish putatively inhabiting blackwater and plainer forms clearwater environments. Zarske (2014) found the two forms to be identical in terms of morphology an…

The majority of records pertain to the rio Guaporé (Río Iténez in Bolivia), the main affluent of the rio Mamoré, which drains the vast tropical wetland known as the Pantanal, and the upper rio Paraguai, which also has its headwaters in the Pantanal but flows in the opposite direction. The Guaporé and Paraguai are connected due to rising water levels during the annual wet season.