Taxonomy & naming
Sternarchorhynchus yepezi was described by de Santana & Vari in 2010 as part of a sweeping revision of the genus Sternarchorhynchus, published in the Zoological Journal of the Linnean Society under the title "Electric fishes of the genus Sternarchorhynchus (Teleostei, Ostariophysi, Gymnotiformes)." That study more than doubled the number of recognized species in the genus, showing that what had been treated as a handful of widespread forms was in fact a mosaic of many geographically restricted species — S. yepezi among them, confined to the Orinoco basin. The species epithet honors Agustín Fernández-Yépez (1916–1977), a Venezuelan ichthyologist whose earlier work pointed toward this hidden diversity.
The genus sits in the family Apteronotidae, the ghost knifefishes, within the order Gymnotiformes — the New-World electric knifefishes. These are bony fish, but unusual ones: entirely unrelated to the superficially similar Asian featherback and clown knifefishes (Chitala, Notopterus), and defined instead by an electric organ and a ribbon-like anal fin used for locomotion. Within Gymnotiformes, Apteronotidae is distinguished by an electric organ built from modified nerve tissue rather than muscle, which produces the fastest, most refined wave-type discharges in the order. The Catalog of Fishes is the authority for the valid name.
Morphology
Sternarchorhynchus species are immediately recognizable by their long, tubular, downturned snout — an elongation of the face built for probing into sand, mud and leaf litter for buried prey. The body is elongate and laterally compressed in typical ghost-knifefish fashion, tapering to a whip-like tail, with no dorsal fin and no true tail fin; forward and backward movement comes from undulations of a single long anal fin running beneath the body. Like its relatives, S. yepezi is entirely scaleless, its skin smooth and unprotected. FishBase records a maximum length of 11 in total length for the species.
Running along the body is the electric organ, paired with sensory pores across the skin that read the field it produces. Sternarchorhynchus discharges are described as triphasic wave-type signals, and the genus is known to produce low-rate "chirps" — brief frequency modulations of the ongoing discharge — layered onto the steady electric hum. No external sexual dimorphism has been documented for this species; data are sparse.
Habitat
Sternarchorhynchus yepezi is known from the central Orinoco River basin in Venezuela, with FishBase noting a possible extension into the Peruvian Amazon; it is one of seven Sternarchorhynchus species recorded from Colombian Orinoco tributaries near the Gulf of Paria. It is a benthopelagic fish of tropical freshwater, living and foraging near the river bottom rather than in open water.
As with other tube-snouted ghost knifefishes, its long snout points to a life spent probing loose, sandy or silty substrates for hidden prey, in the same warm, dim, often turbid Neotropical river conditions favored by the family generally — water where an electric sense does far more work than eyesight. Beyond the basin-level range and general habits shared across the genus, detailed habitat data for this particular species are sparse.
Feeding
The elongated, downturned snout of Sternarchorhynchus is a specialized tool for extracting small invertebrates — aquatic insect larvae, worms and similar benthic prey — from sand, mud and packed leaf litter, in the same way a probe or forceps reaches into a crevice a blunter mouth cannot. As with other Apteronotidae, foraging is thought to rely heavily on electrolocation: the fish's electric field lets it detect the faint electrical signature of buried prey without needing to see it, an essential adaptation for a nocturnal benthic hunter working in dark or turbid water.
Specific dietary studies for S. yepezi were not found in the available sources; the feeding ecology described here follows the well-documented pattern of the genus and family. No aquarium feeding data exist for this species, which is not established in the hobby.
Mating
Across Apteronotidae, the electric organ discharge doubles as a social and reproductive signal, carrying information about a fish's identity, sex and readiness to spawn, and courtship in well-studied relatives such as the brown ghost knifefish involves frequency shifts and interruptions exchanged between fish in the dark. Sternarchorhynchus itself produces distinctive triphasic wave discharges layered with low-rate chirps, and it is reasonable to infer that these signals play a comparable role in communication and courtship, though this has not been specifically documented for S. yepezi.
No species-specific courtship or spawning behavior has been described in the available literature for this narrow-range Orinoco endemic; data are sparse.
Breeding
There is no documented breeding record for Sternarchorhynchus yepezi in the aquarium or in the wild beyond its classification as an egg-layer typical of the family. Apteronotidae as a whole are only rarely bred in captivity, and this species is not established in the aquarium trade at all, so no husbandry-derived breeding information exists. No parental care has been documented for the family beyond scattering eggs among cover; none is known specifically for this species.
Given the complete absence of aquarium history and the limited literature on this species' reproduction, breeding remains essentially undocumented — a case where the honest answer is that too little is known to say more.
In the aquarium
Sternarchorhynchus yepezi is not an established aquarium fish; unlike the widely traded black ghost knifefish, most Sternarchorhynchus species are deep-channel Amazonian and Orinocan fish rarely, if ever, seen in the hobby. Any specimen that did appear would need the same baseline care as other ghost knifefishes: because it is scaleless, it would require careful attention to water quality and to medications, avoiding copper-based treatments and using reduced doses of anything that stresses a scaleless fish's skin. As a nocturnal, electrolocating predator with a specialized probing snout, it would need soft, sandy substrate to forage in, dim lighting, secure cover, and tankmates too large to be preyed upon at night.
Given how little is documented about this species in captivity, and its status as a narrow-range wild population, keeping it — should it ever appear in trade — should lean heavily on the general Apteronotidae care template rather than any species-specific record, none of which currently exists.
Conservation
Sternarchorhynchus yepezi is assessed as Least Concern on the IUCN Red List, with the assessment dated 14 October 2020. The available source notes do not detail a specific threat assessment beyond the listing itself.
As a narrow-range endemic of the central Orinoco basin, the species belongs to the category of gymnotiforms most exposed to localized pressures — habitat alteration, pollution and changes to river flow within its home basin — even where the current Red List status is favorable. It is not part of the aquarium trade, so collection pressure is not a relevant concern for this species.