German aquarist Frank Schäfer has formally described the small barb known as the Drapefin barb or Neon highfin barb in a recent issue of the journal Ichthyological Exploration of Freshwaters.
The new barb is named Oreichthys crenuchoides, after the prominent dorsal fin in the males of this species that resemble those of the South American sailfin tetra (Crenuchus spilurus).
Oreichthys crenuchoides is known only from the Brahmaputra River drainage in northeast India. The type locality was a river approximately 5 metres wide, with slow-moving, clear water and a muddy substrate.
Males of the new species are territorial, at least during breeding season. They display laterally with their large dorsal fin and sometimes fight using their mouths.
Sneaker males are also known to be present in this species – such males are smaller and resemble the females in colour and the presence of a small dorsal fin.
However, the author reports that isolated sneaker males develop a normal, enlarged dorsal fin if isolated for eight weeks.
Females are reported to swim upside down and attach eggs to the underside of the spawning substrata (leaves, roots or stones).
The author also briefly discusses the presence of other undescribed Oreichthys species from India and Myanmar.
Oreichthys crenuchoides is distinguished from congeners by the absence of a spot or blotch on the anal fin, ½7½ scales between the pelvic-fin origin and dorsal midline, a blunt snout, a large, black blotch at the base of the caudal fin, 11–13 rows of pores on the cheek, enlarged dorsal fin in males and pharyngeal teeth in three rows (1-1-4).
For more information, see the paper: Schäfer, F. (2009) Oreichthys crenuchoides, a new cyprinid fish from West Bengal, India. Ichthyological Exploration of Freshwaters 20, pp. 201–211.