Sternopygus: Greek, sternon = sternon, + Greek, pyge = tail
Sternopygus macrurus is a large and aggressive fish which should be housed alone. Sternopygus macrurus is quite secretive and seems to prefer to remain out of site during the day time by lying up very close to or under bog wood or branches. The fish probably feeds mostly after lights out.
In the wild Sternopygus macrurus feeds mainly on aquatic aquatic insect larva, crustaceans and terrestrial insects. The stomach contents of wild fish have been found to contain fish scales and some plant material. In captivity Sternopygus macrurus is unlikely to accept anything other than live food.
There are no visible differences between the sexes but Sternopygus macrurus is an electrogenic species and there are difference between the electric fields that males and females emit.
Sternopygus macrurus hasn't been bred in captivity. In the wild this fish breeds at the beginning or during the rainy season. The male will defend a territory and try to attract nearby or passing females with an electrical signal. Up to 6000 eggs are laid at one time and these are watched over by the male. The fry become free swimming and begin feeding at seven days old.
The health of the wild population of Sternopygus macrurus has not been evaluated.
pH: 6 - 6.5
dGH: 4 - 15
Temperature: 22 - 28°C (72 - 82°F)
Size: 141cm (56in)
Min tank size: 2400 litres
Difficulty level: Difficult
Aquarium type: Keep alone
Swimming level: All levels
Origin: South America: Amazon and Orinoco River basins
Habitat: Lives in swamps, streams, and rivers with still or sluggish waters.
Species: S. macrurus (Bloch & Schneider)
Long tail knifefish
Synonyms: Gymnotus macrurus, Hildatia brasiliensis, Sternopygus marcgravii.