New remarkable sexually dimorphic miniature species of Hyphessobrycon (Characiformes: Characidae) from the upper Rio Tapajós basin.

A new miniature species of Hyphessobrycon is described from an affluent of the Rio Papagaio, tributary of the Rio Juruena, upper Rio Tapajós basin, Mato Grosso State, Brazil. The new species can be distinguished from its congeners by having a remarkable secondary sexual dimorphism in its live colouration (males are red and females yellow), well-defined and relatively narrow dark midlateral stripe extending from tip of snout to tip of middle caudal-fin rays, absence of humeral blotch, 15-18 branched anal-fin rays and five or six branched pelvic-fin rays. The sexually dimorphic colouration of the new species is briefly discussed regarding its temporal variation.

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 Tapajós, 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.

A new species of Astyanax Baird & Girard (Characiformes: Characidae) from the Rio Paraguaçu basin, Chapada Diamantina, Bahia, Brazil, with comments on bony hooks on all fins.

A new species of Astyanax from the Rio Paraguaçu basin, Bahia, Brazil, is described. This new species is distinguished from its congeners known to occur in Brazilian drainages by the presence of small bony hooks on all fins of mature males. Furthermore, the new species can be diagnosed by its colour pattern, which consists of a unique vertically elongated humeral blotch, a conspicuous dark drop-shaped horizontal blotch over the caudal peduncle, tapering anteriorly and not extending to the median caudal-fin rays, and by the absence of a conspicuous broad dark midlateral stripe. The new species differs further by having the greatest body depth just anterior to the dorsal-fin origin, 32-35 perforated scales in the lateral line and a reduced number of branched anal-fin rays (16-20). Apparently, the new species does not fit into any species complex of Astyanax. The occurrence of bony hooks on all fins of Astyanax is discussed.