Sternopygus macrurus
Longtail knifefish

Sternopygus macrurus occurs in many freshwater bodies in South America. It is known to inhabit the area from the Magdalena River to the Sao Francisco River and western Ecuador. It is also found in the Catatumbo River and the Amazon in Peru. (Ortega and Vari 1986)

Sternopygus macrurus is most common in benthopelagic and freshwater bodies such as swamps, creeks, and rivers with lentic waters. The pH range for S. macrurus is 6.0 to 6.5 and the dH range is 4.0 to 15.0. (Ortega and Vari 1986)

Sternopygus macrurus is a knife-shaped fish. It has a slender body with a tapering tail. The maximum length of the Longtail Knifefish is 100.0 cm in total length. S. macrurus is an electric fish. From the larval stage on, an electric organ and electroreceptors are present. (Kirschbaum 1995)

The male Sternopygus macrurus defends a territory. Just before or during the rainy season, the male will attract a female passing though his territory as a spawning partner. He attracts a female using electric signals from his electric organ. A single mating results in over 6000 eggs. (Hopkins 1972; Provenzano 1984; Kirschbaum 1995)

After four days, the Sternopygus macrurus embryos hatch from the eggs. Seven days later, the larvae make their first feeding. The fish reaches sexual maturity at the age of one year. Mature males are territorial. The species is considered harmless to humans. (Kirschbaum 1995; Moller 1995)

Sternopygus macrurus is a predator of small invertebrates. Its diet is mainly composed of aquatic insect larvae. (Planquette, Keith, and LeBail 1996)

Sternopygus macrurus is commercially important in fisheries and aquariums. (Ortega and Vari 1986)

None.