The smallest and most delicate of the nominal hatchetfishes. The rounded keel is shallower than related species, giving this fish a distinctive elongate profile.

The family Gasteropelecidae is separated from other Characiformes by the following combination of characters: front…

Prior to its description P. kamalika was referred to as P. amphibius, a putatively valid species probably restricted to western India.

It differs from all congeners in the following combination of characters: 4½/1/2½ scales in a transverse line between the mid-dorsal…

Based on current knowledge, it thus remains impossible to deduce whether the group of putative species currently comprising S. jurupari, S. mapiritensis, and S. rhynchitis, plus populations from Amapá and the upper Negro/upper Orinoco region, represent distinct taxa or a single meta-population which can be referred to as S. jurupari sensu lato. Here on SF we include the named species separately, since they continue to be considered valid.

Despite its extensive natural distribution S. lilith is uncommon in the ornamental trade, where it is sometimes referred to as ‘one-spotted demon fish’ or ‘one spot eartheater’.

It can be distinguished from other members of the genus by possessing a single dark blotch on the flank and a prominent ocellus at the caudal-fin base. Among the named species it is most similar to S. daemon, but that species possesses two blotches on the flank.

S. pappaterra is relatively rare in the ornamental trade and much sought after by enthusiasts.

It is easily distinguished from all known congeners by presence of a series of prominent black blotches beneath the dorsal-fin, plus a well-defined dark band extending along the side of the body. In recent genetic analyses its genetic distinctness was strongly supported, with S. jurupari and S. leucosticta its closest relatives.

Recent genetic research has revealed there to be a possibility that although S. mapiritensis is genetically distinct from S. leucosticta, it may turn out to be conspecific with S. jurupari and S. rhynchitis. There appears to be no clear genetic separation between these three putative species nor a form known to aquarists as S. sp. ‘Negro-Alto Orinoco’ which replaces S. mapiritensis in the middle and upper Orinoco, Casiquiare Canal, and upper rio Negro.

Unfortunately diagnostic characters cannot be provided since we have been unable to obtain the type description to date, and little else has been written about this species.

There is also confusion regarding whether C. lamberti, the unidentified ‘C009’, and similar-looking fish collected close to Iquitos are conspecific or not. We include all together here until these issues are resolved.

Known only from the rio Ivaí basin, a tributary of the rio Paraná in Paraná state, southern Brazil.

Type locality is ‘Brazil, Paraná, Cândido de Abreu, rio Maria Flora, tributary to rio Ubazinho, rio Ivaí basin…

Prior to description C. kanei was assigned the ‘C’ numbers C026 and C046.

Among congeners it is most easily-confused with, and sometimes traded as, C. atropersonatus, but can be identified by presence (vs. absence in C. atropersonatus) of dark markings in the anal and caudal fins, presence of numerous, smaller (vs. fewer, larger) dark spots on the body, and an overall darker (vs. paler) base colouration.

It also exhibits morphological adaptations to an existence among rocks in a flowing environment, such as a cryptic colour pattern, reduced spine length in the dorsal and pectoral fins, ventrally-oriented pectoral fins, slightly emarginate caudal-fin, and reduced body depth.

Reduced fin spines and body depth are typical features associated with the related genus Aspidoras, but the…