H. compressus is the type species of the genus Hyphessobrycon but is not well-known in the ornamental trade.

Hyphessobrycon was raised by Durbin in Eigenmann (1908) as a subgenus of Hemigrammus, differing from the latter by the absence of scales on the caudal-fin.

This species has been a popular aquarium fish for a considerable period and virtually all fish traded are now raised commercially for the purpose.

It is easily identified by the characteristic bright red or orange underside of the head, which is more pronounced in adults.

Following Miller and Taylor (1984), the genus Thorichthys is identified…