Gold Wolf Fish

Hoplerythrinus unitaeniatus has an elongate body with a terminal mouth. There is a single dark lateral stripe along the length of the body. There is a single dorsal fin, a single anal fin and paired pectoral and pelvic fins. There is a black ocellular spot on the gill cover. The gold wolffish attains a standard length of 28.5 cm (11.2 in) and a maximum weight of 520 g (18 oz).

Hoplerythrinus unitaeniatus is found in Central and South America. It occurs in the drainages of the Amazon, Magdalena, Orinoco, Paraná and São Francisco rivers, as well as in the coastal drainage systems of Guyana, Suriname and French Guiana. This fish's distribution stretches from Panama south to Argentina, Bolivia and Paraguay. The gold wolffish is found in swamps and creeks with low or no current, and can also be found in flooded savanna.

Hoplerythrinus unitaeniatus is the type species of the genus Hoplerythrinus. This name combines the Greek hoplon, meaning "shield" or "armour", a reference to the infraorbital bones being large and covering the cheeks, with the genus name Erythrinus. These enlarged infraorbital bones are not unique to this genus, and all trahiras have them. The specific name, unitaeniatus, "one banded", is thought to be a reference to the single longitudinal stripe along each flank.