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…

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…

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 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.

This species is a popular aquarium fish and is bred on a commercial basis in several countries, with a selectively-bred albino form also available.

Wild specimens are rarely collected due to the low price of the farmed fish, but the origin of the commercial strain is questionable. The species was considered endemic to the rio Tapajós basin, but in the early 1990s fish appearing identical to the aquarium form were photographed in the…

Its name appears to have been misapplied to similar-looking fishes occurring throughout much of the middle and lower Amazon in Brazil and Colombia, plus the rio Orinoco drainage in Colombia and Venezuela, and coastal systems of the Guianas. Some of these have been described as distinct species (e.g. Hyphessobrycon amapaensis Zarske & Géry 1998; H. eschwartzae García-Alzate, Román-Valencia & Ortega 2013; H. montagi Lima, Couthino & Woziacki 2014), whereas the identity of others remains un…

A beautiful species that's not often seen for sale in the hobby, and is usually a little more expensive than other tetras when available. This is mainly due to the wild caught nature of most specimens entering the trade. It can be a little delicate when initially imported, and is sensitive to deteriorating water conditions in general. As a result, it's not a good choice for the beginner, and should only be added to well-matured tanks.

As with the closely related Hemigrammus, the ta…

This species is an opportunistic omnivore by nature.

The stomach contents of wild specimens from the rio Padauari were composed of fruit remains and aquatic insects with the former constituting 99% and latter 1% of all items consumed.

Stomachs of individuals from igarapé Água Boa cont…