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 appears endemic to and abundant within the upper Suriname River system, Suriname.

Type locality is given as ‘little tributaries of Gran Rio between Ligolio and Awaradam Falls’, this corresponding to a section of the Suriname River, which is known as ‘Gran Río’ in parts of its upper basin, upstream of Brokopondo reservoir and not…

This species is very rarely-traded since collections of fishes for commercial purposes aren’t common in Suriname. It’s a member of the nominal G. surinamensis ‘group’ of closely-related species within the genus and can be identified by a combination of characters including: no dark preopercular marking; six vertical/parallel bars on each flank (normally visible only when the fish are stressed, spawning or preserved); dark, squarish lateral spot positioned within the third vertical bar; sixth (posterior) bar elongate an…

This species is also known as the ‘spraying’, ‘splashing’ or ‘jumping’ tetra and these names are also sometimes applied to its congeners although none of them exhibit a comparable spawning strategy, simply depositing their eggs among vegetation at or around the water surface.

This is the type species of the genus, fairly ubiquitous in the aquarium trade, and represents an excellent choice for the newcomer to fishkeeping since it’s less demanding than most congeners. It’s sometimes referred to as ‘Beckford’s pencil fish’ or ‘brown pencilfish’.

Don’t worry if your fish look different when you switch on the aquarium lights after dark or in the morning as like most Nannostomus species it assumes a cryptic, vertically-barred colour pattern at ni…

This small species is a popular aquarium fish but there is some confusion surrounding its identity. Two colour forms have been traded, one of which also possesses tiny hooks on the fin rays.

It can be distinguished from congeners by colour pattern; the body is rose-coloured, fins red with no black markings, and the ovoid humeral spot is prominent, measuring around half of the body depth.