The majority of records derive from the Río Apure watershed in southwestern Venezuela, where C. habrosus has been collected in the states of Portuguesa, Cojedes, Barinas, Guárico, and Apure. Its distribution in Colombia is less clear but it is known with certainty from the Río Arauca and Río Casanare, the latter a tributary of the lower Río Meta, and it makes sense that it should also be found in other left bank Orinoco affluents between the Meta and Apure, which include the ríos Cinaruco and Capanaparo.

This species’ range is unclear with collection records scarce, although it certainly occurs in the ‘Tres Fronteras’ region of the western Amazon river basin where the borders of Brazil, Colombia, and Peru meet.

Type locality is ‘Lakes of the Isla de Mocagua, Amazon River, near Leticia, Comisaría del Amazonas, 3°54’S, 70°14’W, Colombia’.

Unfortunately, precise diagnostic characters cannot currently be provided since we’ve been unable to obtain the type description, and little has been
Characters said to separate it from species such as C. ambiacus, C. agassizii, C. brevirostris, C. ephippifer, and C. melanistius include a combination of relatively elongated snout, dark spots on body fading in adults, dark anterior dorsal-fin patch extending to upper extremity of fin, and presence of spots in the caudal-fin.

Described from the Río Ampiyacu, a small tributary draining into the main Amazon channel in Loreto Department, northeastern Peru, with additional records from the Yavarí (Javari), Napo, Nanay, and lower Ucayali drainage basins.

All of these are Amazon tributaries, and C. ambiacus appears to occur in most or all affluents of the main Amazon channel between th…

Wild populations vary in colour pattern depending on origin, and some populations have previously been described as distinct species.

A form from Peru has a particularly silvery body colour, for example, while another, marketed as ‘super red’ possesses an unusually long red stripe on the body, extending much of the length of the dark central stripe. A population from around Boa Vista in the rio Branco system, Pará state, Brazil has an ocellus o…

There also exist a number of minor differences in colour pattern between populations. For example some Peruvian forms have yellow pigmentation on the body and fins, and those from Guyana and Suriname possess a short red stripe on vertical scale rows 6-9, above the central dark stripe on the body.

Rio Negro forms have a similar red stripe but overlapping the central dark stripe and extending along most of the flank, while a form from Colombia has an elongate red stripe which is broken in two beneath the dorsal-fi…

This species has been referred to the genera Poecilobrycon and Nannobrycon in the past and in the aquarium hobby is also known as ‘rocket’, ‘brown’, ‘brown-tailed’, ‘diptail’, or ‘tubemouth’ pencilfish.It’s a popular aquarium fish and has an interesting oblique swimming-style, a behavioural trait shared only with N. unifasciatus among congeners.

In the original description the colour pattern is given by Steindachner as a brown lateral stripe exte…

This species is not recommended to those lacking the facilities to house it for life. Sadly it’s all too often seen for sale as an attractive, silvery 2-3″ juvenile, supposedly suitable for the general freshwater community tank. To make matters worse, it is also usually given an ‘alluring’ name such as ‘black-finned’ or ‘silvertip’ shark catfish. The fate of the majority of these specimens is in all likelihood a depressing one.

This species appears to be a relative ecological generalist. During a sampling trip in 1989 it was collected various habitat-types including a narrow (maximum width 3 m) stream containing shallow (maximum depth 1 m), transparent, moderate to fast-flowing water and substrate comprising gravel, mud, clay and organic debris including submerged logs. Aquatic plants consisted of water lilies and marginal vegetation was dense, comprising various trees, shrubs, grasses and ferns.

This undescribed species was first collected and subsequently appeared in the aquarium hobby during 2008. It was exported again in late 2009 and early 2010 under the names A. sp. 'Jutai' and A. sp. 'diamond face', and said to have been collected in the Río Jutai, Amazonas state, Brazil. The Jutai is a south bank tributary of the Solimões but lies several hundred kilometres downstream of Leticia so this information, from a purportedly trustworthy source, initiall…