The genus Acarichthys remains monotypic and was resdescribed by Kullander (1986) who characterised it by the following: lack of epibranchial lobe; comparatively few (12-14)rays; pelvic fins with relatively broad tips (branches of the first ray are equal in length or the inner is slightly longer); possession of a single supraneural plus 14-15 vertebrae (these characters taken as a combination); no caudal extensions to swim bladder; no caudal ribs.

Its current taxonomic position is based largel…

It was initially going to be described as Hyphessobrycon cardinalis by Myers and Weitzman (1956) but just before this was due to be published Schultz presented an alternative description in the hobbyist magazine ‘Tropical Fish Hobbyist’ and named the fish after the publication’s founder, Dr. Herbert R. Axelrod.

A significant proportion of the fish available in the aquarium trade are still wild caught or derive from community-led breeding projects such as Project Piaba in the middle Negro region, where this sp…

Given its eventual size and natural behaviour this species is largely unsuitable for the home aquarium, and we know of only a handful of private aquarists with the facilities required to house it long-term.

Unfortunately juveniles are readily available in the trade, although the scarcity of privately-maintained adults would suggest that most fail to reach their potential.

M. ramirezi is also known by the names ‘Ramirez’ dwarf cichlid’ and ‘butterfly cichlid’ and is among the more popular dwarf cichlids in the aquarium hobby.

As a result, it is produced on a commercial basis in huge numbers and a number of ornamental strains have been developed including ‘gold’, ‘long-finned’ (both blue and gold forms; also traded as ‘lyre-tail’, ‘veil-tail’ and ‘hi-fin’), ‘electric/neon blue’, ‘super neon blue gold’ ‘pearl/perlmutt’ and ‘balloon’.

Brachyplatystoma spp. are distinguished from all other catfishes by two synapomorphies. The first comprises several morphological characters relating to the skull, specifically that the mandibular suspensorium (that which connects the lower jaw bone to the skull) is greatly expanded mediodorsally to form a large plate approaching the parasphenoid bone, with the hyomandibula and metapterygoid similarly enlarged.

Famed as a rapacious predator capable of rapidly stripping flesh from bone and a danger to any animal entering its native waters, P. nattereri is among the most notorious freshwater fishes in the world. As a result, displays featuring this “bloodthirsty” creature are found in most public aquaria, grisly Hollywood movies have been released, and the species has become popular in the aquarium trade. Little of this infamy is based on factual evidence, however.

This species lends its name to the ‘G.‘ steindachneri, an assemblage of closely-related species with unresolved generic placement which currently also includes ‘G.‘ crassilabris and ‘G.‘ pellegrini. It exists in a number of colour forms which vary with locality, some of which may eventually be described as separate taxa. Some of these may appear on trade lists under the synonym Geophagus hondae.

S. daemon is relatively common in the aquarium trade but is by no means easy to maintain, with particular attention to space, diet, water quality, and chemistry required in order for it to thrive.

It can be distinguished from other members of the genus by possessing two dark blotches on the flank and a prominent ocellus at the caudal-fin base. Among the named species it is most similar to…