Apparently this species is polymorphic with body patterning varying significantly depending on locality. Individuals collected from black water habitats tend to be noticeably darker in overall colouration, for example, with this being particularly evident among populations from the Guiana Shield.

The genus Ageneiosus was at one point classified in…

This species is among the few members of the family to have been exported for the aquarium hobby. It can be differentiated from all other Akysis species by the following combination of characters: head length 17.7-26.5% of standard length (SL); head width 25.4-28.7% SL; body depth at anus 13.0-17.0% SL; caudal peduncle depth 8.1-10.1% SL; interorbital di…

As in other members of the genus body colouration in this species is variable, even among individuals collected from a single locality, although a few regularities have been observed which can be used to distinguish certain species from one another. This is thought related to the fact that Acrochordonichthys spp. periodically shed their skins and appear paler post-moulting.

The genus Ageneiosus was at one point classified in the family Ageneiosidae alongside the genus Tetranematichthys, but this was not accepted by all authors. The grouping remains poorly-studied with the last major revision having been conducted by Watson (1990) in his unpublished dissertation, in which A. inermis was included under the currently synonymous name A. brevifilis. It can be separated from the majority of the genus (except A. marmoratus) by possession of a truncate caudal fin, and from…

Although often sold as the closely related F. acus (a species that is highly endangered and imported very rarely, if at all), F. vittata is the most common representative of the genus in hobbyists' tanks. The easiest way to distinguish the two is by comparing the shape of the rostrum, which is longer and more slender in vittata, although there are also differences in the arrangement of the ventral scutes. They are adapted for life among peripheral vegetation and tree roots along the edges o…

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…

This species is also known by the alternative vernacular name of ‘Zamora woodcat’, and is often misidentified as A. thoracatus. The latter is a valid species and very similar to A. coracoideus in that the coracoid bone is exposed ventrally and covered only by a thin layer of integument in both species. The two differ principally in the number of anal fin rays…

P. apogon has formerly been placed within the genera Kryptopterus, Micronema (Rainboth, 1996) and more recently Phalacronotus (Ferraris, 2007) and is an important food fish across much of its native range.

It’s very similar to P. micronema but can be told apart by its longer head (HL fits 4.6± 5.3 times in…

This species has been available in the trade for decades during which time it’s been widely misidentified as the valid congeners K. bicirrhis or, more recently, K. minor.

Its identity was not resolved until early 2013 meaning you will find it under one of these two names in the majority of literature published prior to that date.

Other trade names include ‘Asia…

Known from the Malay Peninsula and Singapore plus Greater Sunda Islands of Sumatra, Borneo and Java in Indonesia with populati0ns from Thailand, Cambodia, Laos and Vietnam formerly considered as conspecific now referred to K. geminus (Ng, 2003).

Type locality is given as ‘Bandjarmassing’ which corresponds to a town now more commonly referred to as ‘Banjarmasin’ in South Kalimantan (Kalimantan Selatan) province, Indonesia (Borneo).