Fin's Fish Guide
The Longtail knifefish (Sternopygus macrurus) is a freshwater fish of the family Sternopygidae that grows up to 141 cm.
Fresh water of Central and South America, in slow-moving, densely vegetated water of rivers, creeks and swamps.
Description
The longtail knifefish is a knife-shaped freshwater fish of the family Sternopygidae (glass knifefishes) reaching about 1.4 metres. The elongate, laterally compressed body lacks a dorsal fin and has a very long anal fin with which the fish swims smoothly forward and backward in undulating movements. Like related knifefishes it generates a weak electric field with an organ in the tail, with which it navigates in turbid water, detects prey and communicates with conspecifics; males and females differ in the frequency of their signals. The species comes from Central and South America and lives in slow, densely vegetated water of rivers, creeks and swamps. At night it hunts insect larvae, small crustaceans and worms.
Frequently asked questions
How do you recognise the Longtail knifefish?
The Longtail knifefish has an elongate, eel-like body, is mainly brown and shows a plain pattern. Knife-shaped freshwater fish without a dorsal fin, with a very long anal fin; generates a weak electric field to navigate and communicate.
Where does the Longtail knifefish live?
The Longtail knifefish lives in fresh water and is mostly found around algae or seagrass beds. Fresh water of Central and South America, in slow-moving, densely vegetated water of rivers, creeks and swamps.
How big does the Longtail knifefish get?
The Longtail knifefish grows to a maximum of about 141 cm.
Is the Longtail knifefish dangerous to humans?
No, the Longtail knifefish is harmless to humans. None required: this species is harmless to humans.
Is the Longtail knifefish edible?
The Longtail knifefish is rarely eaten.
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All data
Identification
Appearance
Habitat & distribution
Behaviour & biology
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Status & sources
Same genus Sternopygus
More from the family Sternopygidae
Want the complete picture on the Longtail knifefish?
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