Retroculus spp. are unsuitable for the standard community aquarium, and should be maintained in a set-up designed to resemble a flowing river. The substrate should be composed of soft sand mixed with small pebbles if the aim is to breed the fish (see ‘Reproduction’). Rocks, boulders, roots, branches, and aquatic plants can also be added, although the la…

This small species can be told apart from the similar-looking congener C. habrosus by possession of 4-5 (vs. 2-3) dark markings along the side of the body.

This species was known as L. sp. ‘Buckelkopf’ in the aquarium hobby prior to publication of its official description.

It’s distinguished from all congeners by possessing 7-8 dorsal-fin rays (vs. 9–10 in L. dorsigera, L. fulvipinnis and L. thayeri, 8–9 in L. curviceps and L. flamannellus, and 9–11 in L. flavilabris).

It’s known by various vernacular names including ‘Pirá-pacu’, ‘Pira-pucu’ or ‘Diente de cao’ (central Amazon), ‘Bicuda’ or ‘Uena’ (rio Tocantins), ‘Bicuda’ (rio Tapajós), ‘Aguejeta’ or ‘Picua’ (Venezuela), and ‘Moruwi’ or ‘Pirapoko’ (Guyana).

The entire dorsal-fin base is located anteriorly to a vertical through the anal-fin origin and this character distinguishes it from all other ctenolucids except B. lucius and B. xyrekes.

An obligate piscivore capable of consuming quite large prey in relation to its body size although it tends to focus on smaller prey such as tetras and related species.

Newly-imported specimens may refuse to accept anything but live fishes although most can be weaned onto dead alternatives once they recognise them as edible, and some even learn to accept dried foods.

T. stellatus is superficially similar to its only congener T. securis, but can immediately be identified by the presence (vs. absence) of a prominent dark spot in the dorsal-fin. It is sometimes traded as ‘platinum hatchetfish’.

The genus Thoracocharax was originally erected by Fowler in 1906 as a subgenus of Gasteropelecus, but was elevated to generic status by Weitzman (1960).

This species may be referred to using a variety of names including ‘scomb’, ‘sabre tooth tetra’, ‘sabre tusk barracuda’, ‘dog tooth characin, ‘vampire fish’, ‘Cachorra’ or Pirandirá (the latter two names being used in Brazil where they’re also applied to congeners).

It’s regularly confused with the payara, H. armatus, though that species grows considerably larger, is pop…

This species is sometimes referred to as ‘false corydoras’ or ‘sixray corydoras’.

A. pauciradiatus can be distinguished from congeners by possession of 6 soft dorsal-fin rays, as opposed to 7 in other Aspidoras species, plus its distinctive colour pattern.

Aspidoras species are distinguished from the very…

This species is also referred to as ‘South American puffer’, ‘SAP’, ‘Amazonian puffer’, ‘Peruvian puffer’, or ‘Brazilian puffer’ in the ornamental trade.

Within the genus Colomesus, C. asellus can be immediately identified by possessing a unique transverse row of dermal flaps across the chin which is absent in its congeners C. psittacus and C. tocantinensis.

This is the type species of the genus Aequidens and has the widest distribution of any member species. It exists in various colour forms depending on locality with variants from Ecuador and Peru being particularly sought after since they develop striking red (Ecuador) or orange (Peru) colouration on the lower part of the jaw, head and anterior portion of the belly whereas those from Brazil tend to have an overall grey/blue/green colouration, for example.

Despite its type status it's long…