Taxonomy & naming
Apteronotus camposdapazi was described by de Santana and Lehmann A. in 2006 as a new species of black ghost electric knifefish from the Rio Tocantins basin in Brazil. It belongs to the family Apteronotidae, the ghost knifefishes, within the order Gymnotiformes — the New-World electric knifefishes, a group of bony fish defined by their electric organs and ribbon-like anal fin rather than by any resemblance to typical aquarium fish. The Apteronotidae are set apart within the order by an electric organ derived from modified nerve cells rather than muscle, producing a fast, continuous wave-type discharge used for electrolocation and communication.
The species was previously placed in the genus Sternarchus, a name now treated as a junior synonym of Apteronotus following the post-2006 taxonomic revision; the valid combination is Apteronotus camposdapazi. Despite the shared common name "knifefish", this fish and its Apteronotidae relatives are not related to the Asian featherback or clown knifefishes (Chitala, Notopterus), which belong to an entirely different order — the resemblance is convergent body shape, not kinship. The species epithet honors Ricardo Campos-da-Paz, the ichthyologist credited with discovering it. The Catalog of Fishes is the authority for the valid name.
Morphology
Apteronotus camposdapazi shares the family's blade-like, laterally compressed body, with no dorsal fin and no true caudal fin — locomotion comes from a long anal fin run as a travelling wave along the underside of the body, allowing smooth forward and backward swimming alike. Detailed size data for this species is sparse in the available literature, consistent with a fish that is rarely encountered outside taxonomic surveys of the Rio Tocantins basin.
The original description diagnoses the species by a distinctive pattern: a white or yellow band across the chin, a light patch on the mid-dorsal surface of the head, two light bands on the caudal peduncle, and a light brown band running along the mid-lateral body. As in other Apteronotidae, the skin is scaleless and carries the sensory pores that read the fish's own electric field. The original description also notes sexual dimorphism in head morphology between mature males and females, a trait documented across several Apteronotus species tied to the electric organ and its role in signalling.
Habitat
This species is endemic to the Rio Tocantins basin in Goiás, Brazil, part of the broader pattern in Apteronotidae of narrow-range, single-basin endemism. Like its relatives it is presumed to occupy the benthopelagic zone of flowing tropical freshwater — deeper channels and river margins rather than still water — though fine-scale habitat detail specific to this species is not well documented.
Apteronotidae generally favour warm (roughly 73–82 °F), soft to moderately mineralised, near-neutral to acidic river water that is murky or tannin-stained — conditions where the electric sense, rather than eyesight, is the primary way of navigating and finding food. There is no reason from the available sources to expect A. camposdapazi to differ from this family pattern, but confirmation specific to the species is data sparse.
Feeding
Specific dietary data for Apteronotus camposdapazi has not been documented in the sources available. Ghost knifefishes as a family are nocturnal micro-predators, taking small aquatic insect larvae and other tiny invertebrates located chiefly by electrolocation rather than sight, working over the substrate and among cover after dark.
In the absence of species-specific feeding studies, A. camposdapazi is reasonably assumed to follow this same pattern, but nothing beyond the general family diet can be stated with confidence for this particular species.
Mating
As in other Apteronotidae, reproduction in this species is likely intertwined with its electric sense. The wave-type electric organ discharge that ghost knifefishes use to navigate also carries information about identity, sex and readiness to spawn, and in well-studied relatives such as the brown ghost, males and females shift discharge frequency during courtship in an electrical duet. No courtship behaviour specific to A. camposdapazi has been documented, and the sexual dimorphism in head shape noted in its original description hints that head morphology, alongside electric signalling, may play some role in mate recognition — but this is inference from the family pattern rather than a confirmed observation for the species.
Direct observations of spawning behaviour in A. camposdapazi are not available in the sources reviewed; this remains data sparse.
Breeding
Apteronotus camposdapazi is not established in the aquarium trade and there are no documented captive-breeding records for the species. Apteronotidae in general are egg-layers, spawning among cover such as roots, plants or crevices, and are only rarely bred even in captivity — most trade fish in the family are wild-caught or, for the few species that reach commercial farms, produced under hormone induction rather than natural spawning in home tanks.
No parental care is documented for this species or its close relatives; eggs are scattered and left. Given the complete absence of trade or captive records for A. camposdapazi specifically, its breeding biology in any setting beyond the wild is best described as unknown.
In the aquarium
Apteronotus camposdapazi is not a fish of the aquarium trade — it is known only from scientific collection in the Rio Tocantins basin, and no husbandry information specific to the species exists. Were it ever to appear in the hobby, the general Apteronotidae care pattern would apply: a large, dimly lit tank with abundant cover for a nocturnal, electrolocating predator, warm and softened water, and great caution with medication, since the family is scaleless and unusually sensitive to ammonia, nitrate, and copper-based treatments.
For now this remains a scientifically described species rather than a hobby fish, and any care guidance beyond the family generalities above would be speculation not grounded in the record.
Conservation
Apteronotus camposdapazi is assessed by the IUCN as Data Deficient, reflecting how little is known about its population size, trends and the extent of threats it faces within the Rio Tocantins basin. As a narrow-range endemic restricted to a single Brazilian river basin, it belongs to the category of gymnotiform most exposed to localized pressures — habitat change, damming, pollution and deforestation — even though none of these has been specifically quantified for this species.
With no population data and no documented trade pressure, the most accurate statement is that its conservation status is genuinely unresolved rather than reassuring; further survey work in the Tocantins basin would be needed before its status could be upgraded from Data Deficient with confidence.