Taxonomy & naming
Adontosternarchus duartei was described by de Santana & Vari in 2012 (Copeia 2012(3):535–540), part of a revision of the ghost knifefish genus Adontosternarchus within the family Apteronotidae, order Gymnotiformes — the New-World electric knifefishes. The species epithet honours Cleber Duarte of Brazil's Instituto Nacional de Pesquisas da Amazônia (INPA). The genus name Adontosternarchus reflects the toothless ("a-" without, "odonto-" tooth) condition shared by its members, set within Sternarchus-allied ghost knifefishes.
The Gymnotiformes are bony fish but an unusual lineage, defined by their electric organs and ribbon-like anal fin rather than by any resemblance to typical aquarium fish. Within the order, the Apteronotidae are distinguished by an electric organ derived from modified nerve cells rather than muscle, giving them the fastest, highest-frequency discharges of any knifefish group. Despite the shared common name, gymnotiform "knifefishes" are not related to the Asian featherback or clown knifefishes (Chitala, Notopterus), which belong to an entirely different order; the similarity in body shape is convergent, not a sign of kinship. FishBase records the species with 162–171 anal soft rays, a count used to separate it from its congeners.
Morphology
Adontosternarchus duartei is a modestly sized ghost knifefish, reaching a maximum recorded total length of about 7.5 in, far smaller than showpiece relatives like the black ghost. As in other Apteronotidae, the body is a laterally compressed, blade-like wedge with no dorsal fin and no distinct tail fin; locomotion comes from a very long anal fin running most of the underside, thrown into travelling waves that let the fish move forward or backward with equal facility. The skin is scaleless.
Running beneath the skin along the body is the electric organ, paired with sensory pores that detect the field it produces — the sensory system these fish rely on in place of vision in the dark water they inhabit. Detailed external sexual differences have not been documented for this species.
Habitat
The species is known from the Rio Purus system in the central Amazon basin of Brazil, a freshwater, benthopelagic fish recorded at depths of roughly 8 to 22 metres — well below the shallow, root-tangled margins where many aquarium-trade knifefish are collected. This deep-channel habitat is typical of several Adontosternarchus species, which tend to occupy the main river channel rather than floodplain lakes or backwaters.
Like other Apteronotidae, it lives in dim to dark conditions where an electric sense is far more useful than eyesight, and the genus as a whole is associated with warm, tropical Amazonian river water. Specific water chemistry data for A. duartei were not available in the sources consulted; conditions in the Rio Purus system are broadly consistent with other Amazonian blackwater and whitewater tributaries.
Feeding
Dedicated dietary studies for Adontosternarchus duartei were not found. Ghost knifefishes as a group are nocturnal predators of small invertebrates — aquatic insect larvae, worms and small crustaceans — located by electrolocation rather than sight, an approach consistent with the deep, dark river channels this species inhabits. Given its toothless jaws (reflected in the genus name), it is likely a fish that takes soft-bodied prey rather than anything requiring a grasping bite, but this has not been confirmed for the species specifically. Data sparse.
Mating
Courtship and spawning behaviour have not been documented for Adontosternarchus duartei specifically. What is understood about reproduction in ghost knifefishes generally comes from electrophysiological research on related genera: the electric organ discharge functions as more than a sensing tool, carrying information about a fish's identity, sex and physiological state, and in well-studied Apteronotidae, discharge frequency shifts during social encounters function as a kind of electrical signalling between individuals. Research on Adontosternarchus itself has focused on phase-locking behaviour in its wave-type discharge (700–1500 Hz) rather than on courtship or spawning, so whether this signalling extends to mate choice in this species is not established. Data sparse.
Breeding
No breeding records exist for Adontosternarchus duartei in the sources consulted, and the species has essentially no presence in the aquarium trade. As an apteronotid it is presumed to be an egg-layer like its relatives, but nothing is documented about spawning site, egg number, or parental care, and no aquarium or hormone-induced spawning has been reported. This is a case where honesty matters more than a tidy narrative: the breeding biology of this species is effectively unknown, and the citable fact about its electric organ is neurophysiological (phase-locking of the wave-type discharge), not reproductive.
In the aquarium
Adontosternarchus duartei is not established in the aquarium hobby; it is a deep-channel Amazonian species known primarily from scientific collections rather than trade shipments. General care principles for the genus, extrapolated from the related Adontosternarchus clarkae, point to warm water in the range of 75–82 °F, dim lighting, and secure cave or tube hides that let the fish retreat from light during the day, consistent with its nocturnal, electrosensory lifestyle.
As with all Apteronotidae, it is scaleless and would be expected to be sensitive to ammonia and nitrate, and to copper-based medications, which should be avoided or heavily reduced if ever needed. Because so little is documented about this particular species in captivity, anyone encountering it would be working largely from genus-level inference rather than species-specific experience.
Conservation
Adontosternarchus duartei is assessed by the IUCN as Least Concern, an assessment dated 7 November 2018. This reflects the absence of known major threats to the species within its Rio Purus range in the central Amazon basin of Brazil, rather than an assessment of abundance.
As with many narrow-range Amazonian fish, ongoing pressures on the wider basin — deforestation, water pollution, and hydrological changes from damming — are the kinds of threats that could affect a single-basin endemic like this one over time, even where no immediate decline has been documented. There is no evidence the species is targeted by the aquarium trade, which removes one common pressure faced by more popular knifefish relatives.