At time of writing there exists no scientific evidence that the different populations of this species seen in the aquarium trade (see 'Distribution') represent anything other than a single, widely-distributed species although some exibit minor morphological differences including relative body depth, longer fin rays in the unpaired fins and yellow or orange colouration in the paired fins. There is apparently a form from the upper rio Negro which may turn out to be distinct but it's…

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 a member of the putative A. nasutus group of closely-related species within the genus alongside A. nasutus, A. maculipinna and A. isalineae.

These are characterised by possession of two dark, longitudinal stripes, one running from the tip of the snout to the base and the other from the posterior edge of the lower maxilla to the underside of the caudal peduncle.

An obligate piscivore capable of consuming quite large prey in relation to its body size although it tends to focus on smaller prey such as tetras and related species.

Newly-imported specimens may refuse to accept anything but live fishes although most can be weaned onto dead alternatives once they recognise them as edible, and some even learn to accept dried foods.

This species is not normally aggressive towards conspecifics with juveniles in particular exhibiting a marked schooling instinct.

Older individuals tend to be more solitary but still group together from time-to-time, and it’s best maintained in numbers of four or more.

One important point to note is that acestrorhynchids are can…

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 The grouping remains poorly-studied with the last major revision having been conducted by Watson (1990) in his unpublished dissertation, in which A. inermis was included under the currently synonymous name A. brevifilis.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…

This species, which may also be referred to by the alternative vernacular names 'spiny catfish', 'painted talking catfish' or 'chocolate raphael', isn't particularly common in the trade and most often exported only as bycatch among shipments of Platydoras armatulus. It appears very similar to A. cataphractus with the most useful external distinguishing character being the presence of pale blotches on the dorsal surface, between the dorsal and caudal fins, in….

This is one of the commoner "otos" seen in the hobby, and is an ideal species for the planted aquarium. Unfortunately it can be quite delicate when first imported, and losses are not uncommon. This is usually down to lack of food, as it's a small fish and needs to feed almost constantly, so it's easily starved during transportation. As almost all otos are wild caught, they can be quite sensitive to water quality, too. Many hobbyists report fewer problems if the fish are added…

L136 and its variants are collected in the rio Negro basin, Amazonas state, Brazil, and in particular the rio Demini, a northern tributary flowing into the central Negro in the municipality of Barcelos.

Collection details for LDA05 and LDA06 are currently unclear but presumably in the vicinity.

This unidentified ‘species’ is highly variable in terms of colour pattern, and it has been assigned a ser…

H. inspector can be told apart from other described species in the genus by the following combination of characters: colour pattern comprising brown to black base with large whitish to yellow spots; adpressed dorsal-fin not reaching the adipose-fin spine; spots on head much smaller than on rest of body; spots in the upper caudal-fin lobe combining to form bands in adults; 24 plates in the mid-ventral series.