Taxonomy & naming
Sternarchorhynchus jaimei was described by de Santana & Vari in 2010, one of many tube-snouted ghost knifefish species erected as that genus was revised and split apart in the 2000s and 2010s. 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 an electric organ and a single long ribbon-like anal fin rather than by any resemblance to other aquarium fish. Within the Apteronotidae, the genus Sternarchorhynchus is set apart by its distinctively elongated, tubular snout, used to probe into crevices and sediment for food.
The common name "knifefish" is shared with the unrelated Asian featherback and clown knifefishes (Chitala, Notopterus), which belong to a different order entirely; the resemblance between the two groups is convergent, not a sign of relationship. The Catalog of Fishes (Eschmeyer, CAS) is the taxonomic authority for the valid name Sternarchorhynchus jaimei; the species has no junior synonyms noted in the available sources.
Morphology
As in other Apteronotidae, Sternarchorhynchus jaimei has the classic ghost-knifefish silhouette: a laterally compressed, blade-like body with no dorsal fin and no distinct tail fin, propelled by a long anal fin that runs along most of the underside. What distinguishes the genus at a glance is the snout — drawn out into a slender, tube-like extension well beyond the mouth, the feature that gives Sternarchorhynchus its name ("tube-snouted knifefish"). Females of the species reach a maximum recorded length of about 8 in total length, a modest size for the genus.
Running beneath the skin along the body is the electric organ, in Apteronotidae built from modified nerve tissue rather than muscle, which lets the family produce an unusually fast, high-frequency, continuous wave-type discharge. Sensory pores studding the head and body read the distortions of the surrounding field. Like other gymnotiforms the species is scaleless, a detail with real consequences for how any such fish would need to be kept and medicated.
Habitat
Sternarchorhynchus jaimei is known from freshwater river systems in Brazil, within the wider Amazon basin. The genus as a whole is associated with both whitewater and blackwater river environments, including tributaries such as the Tefé River, and tends to occupy deeper channels and benthopelagic zones over the riverbed rather than shallow margins.
These are the warm, often tannin-stained or turbid waters typical of Amazonian rivers, conditions in which vision is of limited use and an electric sense becomes the primary way of navigating and finding food. Specific water-chemistry data for this species is not available in the sources consulted here; broader Apteronotidae habitat data point to warm, soft, near-neutral to acidic river water as the general pattern for the family.
Feeding
Sternarchorhynchus species forage over and within river substrates, taking aquatic insect larvae and other small invertebrates from the riverbed — a diet consistent with the trophic level reported for S. jaimei on FishBase, which places it as a carnivore. The long, tubular snout typical of the genus is thought to aid probing into crevices, leaf litter and fine sediment to reach prey that a shorter-snouted relative could not reach.
As with other ghost knifefishes, prey location almost certainly relies heavily on electrolocation rather than sight, detecting the electrical signature of buried or hidden animals in the dark, silt-laden water the genus inhabits. No aquarium feeding data exists for this species, since it is not established in the hobby.
Mating
No species-specific courtship or spawning behaviour has been documented for Sternarchorhynchus jaimei. Across the Apteronotidae generally, the electric organ discharge doubles as a social signal alongside its sensing role, carrying information about a fish's identity, sex and reproductive state, and in well-studied relatives such as the brown ghost knifefish courting pairs are known to shift their discharge frequencies in a kind of electrical duet. It is reasonable to expect a broadly similar pattern of electric-signal-mediated courtship across the family, but this has not been confirmed for S. jaimei itself, and the point should be read as inference from the family, not observation of the species.
Breeding
There is no documented breeding record for Sternarchorhynchus jaimei in aquaria or otherwise; data is sparse to the point of absent. Apteronotidae as a family are egg-layers that spawn among cover such as roots and crevices, and captive breeding across the family is rare — most trade individuals of the better-known genera are wild-caught or, occasionally, farm-produced under hormone induction. No parental care is documented for the family. Given that S. jaimei is not present in the aquarium trade at all, none of this can be stated as confirmed fact for the species specifically, only as the general pattern for its relatives.
In the aquarium
Sternarchorhynchus jaimei is not an aquarium fish. It is a deep-channel Amazonian species with no established presence in the trade, and the sources available give no husbandry data. What can be said is general to the family: Apteronotidae are scaleless and require careful handling of medications, avoiding copper-based treatments and using reduced doses of anything else, along with strict control of ammonia and nitrate. They are nocturnal, electrolocating predators that need dim lighting, secure cover and, in any species that were to be kept, tankmates too large to be hunted after dark.
Given its Critically Endangered status and complete absence from the hobby, S. jaimei should not be sought as an aquarium fish; its value here is as an illustration of the diversity hidden within a genus most aquarists will never encounter outside the black ghost's larger, better-known relatives.
Conservation
Sternarchorhynchus jaimei is assessed as Critically Endangered (CR) on the IUCN Red List, an assessment dated November 7, 2018, made under criteria B2ab(ii,iii) — indicating a restricted geographic range together with an observed or projected decline in the area, extent and quality of its habitat. This is a serious classification, consistent with the pattern seen across many gymnotiforms with narrow, single-basin distributions: it is the range-restricted river endemics, not the widespread genera, that carry the real conservation risk in this order.
The species is known only from Brazilian freshwater systems within the Amazon basin, where pressures typical of the region — habitat alteration, deforestation and water-quality decline — plausibly underlie the assessment, though the sources consulted here do not detail the specific threats considered by the assessors. As a Critically Endangered, non-traded species, S. jaimei is a conservation concern rather than a hobby prospect.