C. carsevennensis has formerly been synonymised with C. arnoldi but was considered separate by Zarske (2011) using the following combination characters: absence (vs. presence) of a silvery-white to white patch in the centre of some of the flank scales in males, particularly in the lower half of the body; absence (vs. presence) of a horizontal dark body bar in nuptial males; absence (vs. presence) of thin black margins in the dorsal, ventral and anal fins; eggs deposited among submerged vegetation (vs. eg…

This species does appear in the aquarium trade from time-to-time, often among shipments of other wild-caught fishes from the Orinoco basin.

Populations from Colombia were formerly referred to as C. metae until Zarske (2011) synonymised the two when designating a lectoty…

This species is quite common in the aquarium trade although normally misidentified as the congeners C. nattereri or the very similar C. meinkeni.

It was considered synonymous with C. nattereri for a number of years and was also referred to as C. cf. meinkeni by Zarske and Géry (2006) befo…

This species has been widely referred to as the congener C. nattereri in aquarium literature both prior to and post-publication of its official description in 2006.

The two can be told apart quite easily by the fact that C. nattereri possesses a dark lateral stripe while C. meinkeni does not.

C. meinkeni can be distinguished from all congeners by the followi…

This species is sometimes traded as C. sp. ‘red line’, ‘spotted tetra’ or as its congener C. nigrofasciata.

In the past it’s name was also widely applied to the fish now identified as C. callolepis and C. meinkeni, and this misidentification continues to an extent although the two are easily-distinguished by the fact that C. nattereri is the only one of the three possessing a dark lateral stripe on each side of the body.

Known from the middle and upper Amazon river basins in Brazil, Peru, Ecuador and Colombia.

Type locality is ‘Amazon River at Obidos, Cudajas, and Tabatinga; Rio Negro, Brazil.’

It apparently practises an interesting reproductive strategy in which the eggs are deposited in a shallow depression excavated from the substrate and guarded by the male.

In live fish colour pattern is perhaps the most useful way to identify N. rubrocaudatus plus the closely-related N. marginatus and N. mortenthaleri. N. marginatus is immediately distinguished from the other two by the fact it lacks red pigmentation on the body in males, but N. mortenthaleri and N. rubrocaudatus are more easily-confused.

Males of N. rubrocaudatus can be told apart fro…

Described from ‘Igarapé Candiru-Mirim, Rio Capim, Pará, Brazil’, a relatively short river draining into the rio Pará near the city of Belem, eastern Brazil.

Records of similar-looking fish exist from Santarém, Pará state, in the central Amazon region, and the coastal city of Fortaleza, Ceará state, much further southeast. These may require confirmation.

Inhabits sluggish blackwater tributaries, small rivers and swampy areas, particularly in areas with dense growth of aquatic or overhanging riparian vegetation, submerged woody structures and leaf litter. The water is typically stained darkly with humic acids and other chemicals released by decaying organic material, the dissolved mineral content is generally negligible and pH can be as low as 4.0.

N. minimus occurs sympat…

This species is also known as ‘Marilyn’s pencilfish’. It’s rarely traded in numbers and more often seen as bycatch among shipments of other species, particularly Paracheirodon axelrodi.

It can be identified by the following combination of characters: three dark lateral stripes (sometimes referred to as primary, secondary, and tertiary); nocturnal oblique bars relatively narrow, with the anterior bar reaching, but not extending past, the anterior base of the dorsal-fi…