This species is relatively rare in the aquarium trade.

It can be differentiated from all congeners by a combination of possessing ctenoid (vs. cycloid) scales on the sides of the head plus lacking a dark spot at the caudal-fin base.

Recorded throughout much of the Amazon basin, with its range extending eastwards from the Ucayali system in Peru as far as the Tocantins drainage which flows into the Atlantic alongside the Amazon at its delta. The southern extremity of its range appears to be the Río Mamoré in Bolivia, a tributary of the rio Guaporé, and the northern limit the Essequibo basin, Guyana.

This is the smallest of three similar-looking species most commonly-referred to as the ‘bleeding heart’ subgroup, the other two being H. erythrostigma and H. socolofi.

All possess a reddish humeral spot which is not present in any other characid with other shared characters including possession of 6 -14 maxillary teeth, 7-9 scales above the lateral line, 5-7 scales below the lateral line and 26-33 anal fin rays.

This species is available on a relatively regular basis, although it’s sometimes confused with the similar-looking congeners H. loretoensis and H. metae.

It can be identified via the following combination of characters as per Géry (1977): elongate in shape with body depth fitting 3.8-3.9 times in its standard length; caudal peduncle narrow, its depth fitting 1.8 times in its length; head short, interorbital broad, snout short and rounded; dorsal-fin insertion an…

C. incolicana was the first recipient of a ‘C’ number (see below) in 1993 and was described the same year. Unfortunately its description was published in an aquarium hobbyist magazine, and we have been unable to obtain a copy to date meaning its diagnosis is unavailable. It is therefore difficult to identify accurately, not least because its type locality is in a relatively remote area, and there exist a number of superficially similar Corydoras species or populations in the aquarium trade.

C. guapore is a sought after aquarium fish although it is not often traded. It exhibits slightly different behaviour to the majority of congeners in that it tends to form aggregations in midwater and spends a large proportion of its time away from the substrate. Its morphology exhibits corresponding adaptations towards a pelagic existence with a relatively large eye, a more terminal mouth position, more strongly-forked caudal-fin, and more symmetrical body shape than most other Corydoras species.

This species’ range is unclear with collection records scarce, although it certainly occurs in the ‘Tres Fronteras’ region of the western Amazon river basin where the borders of Brazil, Colombia, and Peru meet.

Type locality is ‘Lakes of the Isla de Mocagua, Amazon River, near Leticia, Comisaría del Amazonas, 3°54’S, 70°14’W, Colombia’.

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.

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.

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…