Taxonomy & naming
Sternarchorhynchus starksi was described by de Santana & Vari in 2010, in a large revision of the genus published in the Zoological Journal of the Linnean Society that brought the number of recognized Sternarchorhynchus species into the low thirties. It belongs to the family Apteronotidae, the ghost knifefishes, within the order Gymnotiformes — the New-World electric knifefishes, a group of bony fish only distantly related to the rest of the aquarium-fish fauna and defined by their electric organs and ribbon-like anal fin. Within Apteronotidae, the genus Sternarchorhynchus is distinguished by its long, downward-curved, tube-shaped snout, a feature that gives the group its common name of tube-snouted ghost knifefishes.
The genus is one of the more speciose in the family, and its members are difficult to tell apart without close morphological or genetic examination, so revisions like the 2010 paper have repeatedly split what were once treated as a handful of wide-ranging species into many narrower, often single-basin taxa. Despite the shared common name, Gymnotiformes such as S. starksi are not related to the Asian featherback and clown knifefishes (Chitala, Notopterus); the resemblance in body shape is convergent, not a sign of kinship. The Catalog of Fishes (Eschmeyer, California Academy of Sciences) is the authority for the valid name.
Morphology
As in other Apteronotidae, the body of S. starksi is elongated and laterally compressed, tapering to a slender tail, with no dorsal fin and no true tail fin; locomotion comes from a long anal fin run as a travelling wave along the underside of the body, letting the fish move forward and backward with equal facility. The genus's defining feature is its snout: distinctly elongated and curved downward into a narrow tube, an adaptation for probing into sediment, leaf litter and crevices for hidden prey, rather than the shorter, straighter snout of genera like Apteronotus.
The skin is scaleless, as in all Gymnotiformes, and carries the sensory pores that read the electric field produced by the fish's electric organ — in Apteronotidae this organ is unusual in being derived from modified nerve tissue rather than muscle, which is what allows the family's characteristically fast, high-frequency wave-type discharge. Detailed size and coloration data specific to S. starksi were not accessible in the sources used for this profile; congeners in the genus are generally described as slim, elongated fish in the same general size range as other mid-sized Apteronotidae, and this should be treated as data sparse for this species specifically rather than assumed.
Habitat
Sternarchorhynchus as a genus is centred on the Amazon basin, with the great majority of its roughly thirty species found across Amazonian drainages in Bolivia, Brazil, Colombia, Ecuador and Peru; a smaller number of species occur in the Orinoco and Gulf of Paria drainages of Colombia and Venezuela, and single species are known from the Essequibo of Guyana, the Maroni of French Guiana and Suriname, and the upper Paraná of Brazil. The exact type locality and confirmed range of S. starksi itself were not available in the sources consulted here, so its distribution is treated as data sparse and inferred to lie within this broader Amazonian pattern rather than stated as confirmed.
Like other Apteronotidae, the genus is associated with the channels and margins of flowing, often turbid or tannin-stained Neotropical rivers, environments where vision is of limited use and the electric sense does the work of finding food and avoiding obstacles. The long, curved snout suggests a fish that forages close to the bottom and among structure — root tangles, leaf litter and sediment — rather than in open water.
Feeding
Sternarchorhynchus species are generally understood to be nocturnal invertebrate feeders, using their electric sense to locate small prey — aquatic insect larvae, worms and other invertebrates — hidden in sediment, leaf litter or crevices. The genus's elongated, decurved snout is thought to be a specialisation for probing into these tight spaces, a similar ecological role to the tube-snouted feeding style seen in other bottom-probing electric fish.
No diet data specific to S. starksi were found in the sources used for this profile; the feeding notes above draw on general Apteronotidae and Sternarchorhynchus biology from the cache rather than on direct observation of this species, and should be read as inference rather than confirmed record.
Mating
As in other Apteronotidae, the wave-type electric organ discharge in Sternarchorhynchus is very likely to function as a courtship and species-recognition signal, not just a navigation tool — this pattern is well documented in the family's best-studied member, the brown ghost knifefish Apteronotus leptorhynchus, where males and females shift discharge frequency during courtship in a kind of electrical duet and rivals produce distinctive signal interruptions on encounter. Because wave-type discharges are species- and often sex-specific, and are known to be evolutionarily labile across Apteronotidae congeners, it is reasonable to expect S. starksi has its own characteristic discharge used in the same general way.
No courtship behaviour has been directly documented for S. starksi in the sources used here, so this section describes the family-level pattern rather than confirmed observations of this species; it should be read as informed inference, not established fact for this particular fish.
Breeding
Sternarchorhynchus starksi is not known to have been bred in the aquarium, and there is no aquarium trade to draw breeding reports from in the first place. Apteronotidae in general are egg-layers that spawn among cover such as roots and crevices, with no substantial parental care documented in the family, and even the popular, widely-kept black ghost knifefish is only rarely bred outside hormone-induced farm production — a poorly-studied deep-channel Amazonian species like S. starksi should be assumed to be entirely undocumented in this respect.
Given the complete absence of husbandry or breeding data for this species, this account deliberately does not speculate about a breeding protocol; the honest position is that S. starksi's reproductive biology is data sparse beyond the general expectation, drawn from its family, of egg-laying with electric-signal courtship and no parental care.
In the aquarium
Sternarchorhynchus starksi is not an aquarium fish in any practical sense — it does not appear in the ornamental trade, and no husbandry record for it was found in the sources used for this profile. What can be said comes from its family: Apteronotidae are scaleless and consequently need great care with medications (no copper-based treatments, and reduced doses of anything else) and are sensitive to ammonia and nitrate; they are nocturnal, electrolocating predators that need dim lighting, secure cover, and tankmates too large to be treated as prey. A congener sold in the trade under the tube-snouted ghost knifefish name, S. mesensis, is kept at 75–82 °F and pH 6.2–7.2 in tanks of 40 US gal or more, and that general envelope is a reasonable, if unconfirmed, proxy for what S. starksi would require if it were ever available.
Given the total lack of trade or husbandry history, anyone encountering this species — most likely a specialist importer or a public aquarium — should treat it as an advanced fishkeeping proposition on the strength of its family alone: dim, well-filtered, soft-to-moderate, near-neutral water, ample hiding structure, and no small tankmates.
Conservation
Sternarchorhynchus starksi is assessed on the IUCN Red List as Least Concern. Most described members of the genus, and most Apteronotidae generally, are either unassessed or listed as Data Deficient or Least Concern, reflecting how little targeted survey work has been done on this diverse but inconspicuous group of deep-channel Amazonian fish.
The genus as a whole faces the same broad pressures as other Neotropical freshwater fish — habitat alteration from damming, deforestation and mining-related pollution across Amazonian and Orinocan drainages — and species described from single river systems or restricted basins can still be more exposed to local disturbance than wide-ranging genera. No specific threat or population decline has been documented for S. starksi itself.