A name for the ‘blueberry tetra’, an aquarium trade popular species of Hyphessobrycon Durbin (Characiformes, Characidae), with comments on fish species descriptions lacking accurate type locality

A new species of Hyphessobrycon is described from a tributary of the upper Rio Tapajos, Amazon basin, Mato Grosso, Brazil. Its exuberant colour in life, with blue to purple body and red fins, is appreciated in the aquarium trade. Characters to diagnose the new species from all congeners are the presence of a single humeral blotch, absence of a distinct caudal-peduncle blotch, absence of a well-defined dark mid-lateral stripe on body, the presence of 16-18 branched anal-fin rays, nine branched dorsal-fin rays and six branched pelvic-fin rays. A brief comment on fish species descriptions solely based on aquarium material and its consequence for conservation policies is provided.