Araguaia

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.

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.

Despite the ubiquity of its name in aquarium literature, confusion surrounds its true identity. Given it's the only member of the genus occurring on the island, fish from Trinidad do presumably represent C. aeneus (see our image), but the classification of those from other localities appears far from certain. Today the species is accepted to occur throughout much of South America, and indeed similarly-patterned fish do occur across a large portion of the continent. Some of these, such as the gree...

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...

Type locality is 'Rio das Mortes, some 100 km before its confluence with the Braço Maior of the Rio Araguaia (the western border of the Isla do Bananal). State of Mato Grosso.' The das Mortes is a principal tributary of the Araguaia, itself the major affluent of the rio Tocantins within the lower Amazon basin in central and western Brazil, although the full range of H. amandae within the Araguaia system is unclear.

This species is occasionally available in the aquarium trade, although usually as bycatch among shipments of other fishes. It is sometimes traded as H. sp. 'Araguaia red', H. sp. 'Araguaia' or 'Schultz's tetra'.

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...

In the aquarium hobby the name Hyphessobrycon stegemanni has frequently been misapplied to a species that has been described as Hemigrammus ataktos Marinho, Dagosta, & Birindelli 2014. The reasons for this confusion are presumably that the two occur sympatrically in the rio Tocantins system and both possess a dark lateral stripe on the body.

Metynnis lippincottianus is occasionally seen for sale, sometimes under the name of "Silver Dollar". It is easily distinguishable from m. argenteus and m. hypsauchen (which are more commonly sold as Silver Dollars) by its spotted pattern, hence the common name. M. lippincottianus shares a common name with m. maculatus but the two can be distinguished as the spots on m. maculatus are more pronounced. Silver dollars are common and popular fish in the hobby. They are related to piranh...

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...

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 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...

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.

In the Amazon region it is only specimens larger than around 160 cm and werighing in excess of 50 kg that are referred to as 'Piraíba' with the name 'filhote' normally applied to smaller individuals. Other vernacular names include 'Salton catfish', 'Kumakuma'; and 'tiger antenna catfish'; with members of the genus often referred to collectively as 'goliath catfishes'.

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).