Type locality is giev as ‘Rio Parahyba and tributaries at Mendez; Juiz de Fora; River Doce; River São Matheos; Rio Jequitinhonha; Rio Quenda at Santa Cruz’, all of which pertain to localities within the Paraíba do Sul and Doce river systems in Minas Gerais, Espírito Santo, rio de Janeiro and São Paulo states, southeastern Brazil.

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

A natural-style arr…

Type locality is ‘Tukeit, Guyana’, and this species is known from various river drainages of Venezuela, Guyana, Suriname and French Guiana including the Orinoco, Essequibo, and upper Courantyne (aka Corantijn) basins.

Additional records exist from the upper Amazon basin in Guyana, these presumably corresponding to the Takutu river basin, itself part of the upper rio Branco.

Type locality is given simply as ‘Amazon River, Brazil’ and according to current thinking this species has a huge natural range encompassing the Amazon River system in Brazil and Peru plus the Paraná-Paraguay drainage in southern Brazil and Paraguay and rio São Francisco basin in southern Brazil.

Specimens in our images were collected fro…

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…

This species is poorly-known in the aquarium hobby but is sometimes exported as bycatch among shipments of other species, especially Nannostomus beckfordi to which it appears quite similar. The easiest way to tell the two apart is that N. grandis lacks pale white or bluish tips to the ventral fins.

It can be further distinguished from all congeners by the following combination of characters: body size up to 46.2 mm, the largest in the genus; bo…

This species is sometimes traded as ‘Espei’s’, ‘four-barred’ or ‘banded’ pencilfish and is sought after in the aquarium hobby, though normally quite expensive to buy.

It’s most-easily identified by its unique colour pattern of 5 dark, vertically-orientated bar-like markings on each flank, this in direct contrast to the horizontal stripes seen in other congeners…