This species was described from a single specimen and included in the genus Leporinus until 2011 at which point the holotype was examined and recognised as corresponding to the fish described as Synaptolaemus cingulatus (Myers & Fernández-Yépez, 1950).

Décor is relatively unimportant and maintenance simple provided sufficient space is available.

A natural-style arr…

This species is very rare in the aquarium hobby and may never have been available on a commercial basis although it has been collected, bred and distributed by some private collectors.

It’s a member of the putative G. surinamensis ‘group’ of closely-related species within the genus and ca…

In the upper Iténez it most commonly inhabits riparian zones with sandy substrates or edges of sand banks, although it’s also been collected in smaller streams and residual flood waters.

It typically forms large aggregations of up to several thousand individuals and at the confluence of the ríos Paraguá and Iténez occurs sympatrically with the congener C. paragua.

This species can be confused with three similar-looking fishes of uncertain taxonomic status which have been assigned the C numbers C024, C077, and C109 in the aquarium hobby.

C024 and C109 are unlikely to be conspecific in that they occur in Pará state, Brazil, several thousand kilometers outside the range of C. acutus, in the rio Guamá (Tocantins drainage), and lower rio Xingu, respectively.

Native to the central Amazon basin with records existing from the Madeira, Branco, Trombetas, and Tapajós river drainages, plus the Rupununi basin in Guyana. Although an affluent of the rio Essequibo and thus not officially part of the Amazon basin, the latter is connected to the rio Takutu, a tributary of the upper rio Branco, during the annual wet season.

Type locality is given by Fowler as ‘Rio Madeira about 200 miles east of W. Long. 62°20′, Brazil’.

This rich feeding ground is exploited until the sea water returns, at which point the catfishes begin to migrate upstream in massive numbers, moving up the Amazon and its tributaries. Sexually mature individuals are not normally recorded during these events so they’re thought related to feeding and dispersal rather than spawning. The fish are subject to intensive capture by commercial and artisanal fishing operations during this upstream movement.

This species can be told apart from the very similar-looking congener B. filamentosum by its smaller adult size (B. filamentosum can grow to almost 3 m in length), shorter maxillary barbels (never extending beyond base of adipose fin (vs. extending beyond base of adipose fin), moderately-forked with lobes of equal size (vs. deeply-forked caudal fin with upper lobe usually longer than the lower) and body col…

Study of B. rousseauxii has revealed that sexually mature adults are found only in the western Amazon, with no mature individual ever recorded east of Manaus despite the intensive commercial fishery operating there. The total distance covered by some populations during migration from the delta was as much as 5500 km, making it the longest known in any freshwater fish species.

Found in a number of habitat-types, though rarely in smaller tributaries, generally preferring deeper, flowing channels through which it travels for considerable distances at certain times of year. Like other large, migratory pimelodids these movements are typically associated with nutrient-rich, white water drainages rather than nutrient-poor black waters.