Sao Francisco basin

A number of sources state that S. brandtii can be identified by the relatively anterior position of the anal-fin origin beneath the first few dorsal-fin rays. However, images of specimens collected from the rio São Francisco, where it is the only member of the genus present, suggest that this is not always the case and this is also supported by the figure from Eigenmann (1915). No recent diagnosis of the species is available.

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...