Taxonomy & naming
Rhinosternarchus goajira was described by Leonard P. Schultz in 1949, originally placed in the genus Eigenmannia, and later reassigned — most recently to the monospecific genus Rhinosternarchus, having also passed through Distocyclus in intervening taxonomic revisions. FishBase and GBIF records reflect this recent reassignment (2021), and the Catalog of Fishes is the authority for the currently valid combination. It belongs to the family Sternopygidae, the glass and rattail knifefishes, within the order Gymnotiformes — the New-World electric knifefishes, a group of bony fish only distantly related to other aquarium fish and defined by their electric organs and their long, ribbon-like anal fin.
The species epithet goajira refers to the Goajira (Wayuu) Indigenous territory in Venezuela, near where the holotype was collected. The genus name Rhinosternarchus draws on a long, conical snout as a diagnostic feature. Like every gymnotiform, R. goajira produces a weak electric organ discharge (EOD) used for electrolocation and communication; in Sternopygidae this discharge is wave-type — a continuous, near-sinusoidal signal, in contrast to the intermittent pulses produced by families such as Gymnotidae. These New-World knifefishes are not related to the Asian featherback or clown knifefishes (Chitala, Notopterus); the resemblance in body shape is convergent, not a sign of kinship.
Morphology
Rhinosternarchus goajira is a slender, elongate fish reaching a recorded maximum of about 19.5 in in total length, among the larger members of its family. As in all Sternopygidae it lacks a dorsal fin and true tail fin; locomotion is handled almost entirely by a very long anal fin running along most of the underside, thrown into travelling waves that let the fish move forward or backward with equal ease. FishBase records an unusually high anal-fin ray count of 255–263 for the genus, a diagnostic feature distinguishing it from close relatives.
The body carries the electric organ along its length and sensory pores across the skin that read the electric field it produces — the sensory basis for electrolocation in murky or dark water. Like other gymnotiforms it is scaleless, a trait that matters for water quality and medication tolerance wherever the species is kept. Sex differences in external morphology are not documented for this species.
Habitat
This is a narrow-range endemic: Rhinosternarchus goajira is known only from the Lake Maracaibo basin in northwestern Venezuela, specifically its western portion, and is not recorded from any other South American drainage. FishBase describes it as benthopelagic — living in open water near the bottom rather than buried in sediment or tight against structure — within this basin's freshwater habitats.
As with other Sternopygidae, its ecology depends on the electric sense: wave-type electrolocation lets it operate in turbid, dimly lit water where vision is of limited use. Beyond the basic distributional and lifestyle facts recorded by FishBase and GBIF, published habitat detail for this species — water chemistry, seasonal movement, microhabitat — is sparse.
Feeding
No species-specific dietary study has been published for Rhinosternarchus goajira. FishBase assigns it a trophic level of 3.1, consistent with a secondary consumer feeding on small invertebrates, which places it in line with the general pattern for glass and rattail knifefishes: nocturnal micro-predators that locate prey — aquatic insect larvae, small crustaceans, worms — largely through electrolocation rather than sight, in water where visibility is poor.
Given the lack of direct observation for this species, this should be read as an inference from its family and trophic level rather than a documented account of its foraging behaviour.
Mating
Nothing specific has been published on courtship or mate recognition in Rhinosternarchus goajira. In wave-type Sternopygidae generally, the electric organ discharge doubles as a communication signal — carrying information on species and sex identity — and courtship in well-studied relatives such as Eigenmannia is understood to involve exchanges of electric signalling alongside physical approach. Whether that pattern extends to this species has not been documented; it is inference from the family, not observation of R. goajira itself.
Breeding
Breeding biology for Rhinosternarchus goajira is undocumented — there is no record of it having been spawned in captivity or observed spawning in the wild. Sternopygidae as a family are egg-layers that scatter adhesive eggs among plant roots or floating vegetation, typically timed to warmer, softer, higher-water conditions, with little or no parental care afterward; this is the pattern most consistent with the family, but it has not been confirmed for this species specifically. Data on this species is sparse enough that no breeding protocol can honestly be offered.
In the aquarium
Rhinosternarchus goajira has essentially no presence in the aquarium hobby — it is not a traded ornamental species, and the sources available for this account (FishBase, GBIF, taxonomic literature) contain no aquarium-keeping information. Anyone who did encounter this fish should apply the general rules that hold for scaleless gymnotiforms: avoid copper-based medications and use reduced doses of anything else, since scaleless fish are far more sensitive than scaled species; maintain excellent water quality, as these fish are intolerant of ammonia and nitrate; and provide dim lighting and secure cover, since they are electrolocating, largely nocturnal predators uncomfortable under bright light or in the open.
At a recorded maximum length of nearly 19.5 in, this would in any case be a large-aquarium fish, and given its status as a single-basin endemic with no established aquarium trade, keeping it should not be treated as a realistic prospect for most hobbyists.
Conservation
Rhinosternarchus goajira is assessed as Least Concern by the IUCN Red List (as of 2021). This sits somewhat in tension with its very restricted range — endemism to a single lake basin usually raises conservation flags — but reflects that no major population decline or acute threat has been documented for the species within Lake Maracaibo. It has no recorded commercial importance and is not targeted by fisheries or the aquarium trade.
As with other narrow-range endemics of the Maracaibo basin, the general pressures affecting the lake — industrial and agricultural pollution, habitat modification, and the basin's history of oil-industry activity — are the plausible long-term risks to a species with nowhere else to go, though this account does not have a source documenting specific threats to R. goajira itself.