C. caudimaculatus may be confused with the congener C. similis but can be told apart by possession of a well-defined, blackish spot on the caudal peduncle vs. a ‘smudged’ bluish marking.

C. guapore also has a comparable colour pattern but possesses a distinctly rounded snout and tends to swim above the substrate.

This species occurs alongside the similar-looking congener C. oiapoquensis in nature, from which it can be told apart by the following combination of characters: larger adult size; narrower body (body breadth fits 4.0-4.4 times in standard length vs. 3.4-3.8 times in C. oiapoquensis); shorter pectoral spine (3.4-3.8 times in SL vs. 2.7-3.2 times); longer snout (1.7-1.9 times in SL vs. 2.0-2.2).

This species is not well known and rarely traded for the aquarium hobby.

Unfortunately diagnostic characters cannot be provided since we’ve been unable to obtain the type description, and little has been written about this species since it was published. It looks very similar to several congeners, particularly C. acrensis and C. cruziensis.

C. brevirostris was described from an aquarium specimen apparently exported from the Río Orinoco drainage in Venezuela, and its wider distribution is somewhat vague, usually being given as the Orinoco system plus unnamed coastal rivers in Suriname.

This represents a somewhat disjunct pattern of distribution and if correct the species is also likely to occur in Guyana.

Type locality is ‘Río Yuruari, 3 kilometers east of El Callao, 7°18’N, 61°50’W, Bolivar, Venezuela’, and this species is also known from the Rupununi River drianage in Guyana and the Courantyne/Corantijn system in Suriname.

The Yuruari, an affluent of the Río Cuyuni, an…

Fish collected in the upper rio Maderia basin in Brazil and Bolivia have been traded under the invented names C. sp. ‘dorsalis’ and C. sp. ‘ogawae’ in the past, although are officially-considered conspecific with C. armatus.

This appears to warrant investigation since the Río Huallaga in Peru, type locality of C. armatus, and collection localities in the upper Madeira are separated by a straight-line distance of almost 2500 km.

This species is sometimes confused any of several similar-looking fishes such as C. sychri or C. sp. C097.

While the former is a more elongate fish with a longer snout and quite easy to identify, C097 resembles C. atropersonatus more closely, despite being traded as C. sychri ‘longnose’. Its snout is longer than that of C. atropersonatus but shorter than that of C. sychri, and the dark spots on the body tend to be more well-defined and spaced out than in the other two.

Described from the Río Ampiyacu, a small tributary draining into the main Amazon channel in Loreto Department, northeastern Peru, with additional records from the Yavarí (Javari), Napo, Nanay, and lower Ucayali drainage basins.

All of these are Amazon tributaries, and C. ambiacus appears to occur in most or all affluents of the main Amazon channel between th…

This species is sometimes referred to as ‘false corydoras’ or ‘sixray corydoras’.

A. pauciradiatus can be distinguished from congeners by possession of 6 soft dorsal-fin rays, as opposed to 7 in other Aspidoras species, plus its distinctive colour pattern.

Aspidoras species are distinguished from the very…

This species may also be seen on sale as 'Guyana slopehead catfish' 'dolphin catfish' or 'hammerhead catfish'. The attractive juvenile patterning is largely lost as the fish grow but this nevertheless remains an impressive predatory species for the larger aquarium.

The genus Ageneiosus was at one point classified in the family Ageneiosidae alongside the genus Tetranematichthys, but this was not accepted by all…