Kingdom: Animalia
Phylum: Chordata
Superclass: Osteichthyes
Class: Actinopterygii (ray-finned fishes)
Order: Gymnotiformes (Knifefishes)
Family: Gymnotidae (Naked-back knifefishes)

Genus/species: Electrophorus electricus

GENERAL CHARACTERISTICS: This eels (knifefishes) body is elongated and cylindrical, almost without scales; head flattened; mouth large with one row of conical teeth on each jaw; presence of three abdominal pairs of electric organs. The color is dark with anterior ventral part yellowish. They have a very long anal fin.

Large up to 2.5 m (8 feet). Weight up to 20 kg (44 pounds)


DISTRIBUTION/HABITAT: Tropical. Amazon Basin: Orinoco, and related areas in northern South America. Found in lowland backwaters and muddy river bottoms, never fast-flowing waters. During daylight, retreats to recessed hiding places shared with conspecifics.

DIET IN THE WILD: E. electricus juveniles eat invertebrates such as shrimp; adults prey on fish and small mammals.

MORTALITY/LONGEVITY: Life span: in captivity males to 15 years, females to 20+


REPRODUCTION: E. electricus  males construct foam nests and guard the growing larvae. First-born larvae prey on other eggs and embryos coming from late spawning batches. In mid-January when the first seasonal rains flood the breeding area, causing the about 10 cm long young eels to disperse.

REMARKS: NOT A TRUE EEL. True eels lack pectoral and pelvic fins. Unlike “true” eels in the Order Anguilliformes, they are obligate air breathers, taking up to 80% of their oxygen directly from the air, an adaptation for survival in poorly oxygenated water. The long undulating anal fin allows the electric eel to move backwards or forwards.

Though not an aggressive fish, can produce enough voltage to severely injure humans. If an electric eel fires a series of charges, each successive charge is less powerful. Aquarists stimulate several discharges before attempting to handle the animal safely. These eels also have two other, much smaller sets of electric organs, used for orientation, finding prey.
Active nocturnally.

The long undulating anal fin allows the electric eel to move backwards or forwards. About half the musculature has been converted into electric organs which produce up to 650 V. These eels use their electricity to stun the fish they prey upon, as well as for defense.

As the eel (knifefish) matures it develops cataracts leading to blindness relying only on its electrical senses. (Similar to the elephant fish with poor vision).

CONSERVATION: IUCN Red List; Least Concern.


California Academy of Sciences Steinhart Aquarium Flooded Amazon 2018

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