Arari

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...

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.

This species is currently the only described member of its genus although colour pattern and morphology vary considerably across its range. You may see reference to this species being the only fish species to possess infra-red vision, but other species also possess this ability and we suspect that infra-red plays an important role in the reproductive cycle of many fishes.

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 is the type species of the genus Aequidens and has the widest distribution of any member species. It exists in various colour forms depending on locality with variants from Ecuador and Peru being particularly sought after since they develop striking red (Ecuador) or orange (Peru) colouration on the lower part of the jaw, head and anterior portion of the belly whereas those from Brazil tend to have an overall grey/blue/green colouration, for example. Despite its type status it's long...