Taxonomy & naming
Sternarchorhynchus curvirostris was described by George Albert Boulenger in 1887, with its type locality at Canelos, Ecuador. 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 their long, undulating anal fin rather than by any resemblance to typical fish body plans. Within Apteronotidae, the electric organ arises from modified nerve cells rather than muscle tissue, giving the family the fastest and most refined electrolocating sense of any knifefish group.
The genus Sternarchorhynchus comprises roughly thirty species of tube-snouted ghost knifefish, more than two-thirds of them restricted to the Amazon basin (including the Tocantins) across Bolivia, Brazil, Colombia, Ecuador and Peru. S. curvirostris is treated as the nominal member of a tentatively recognized "S. curvirostris species group," a cluster of closely similar forms that also includes S. roseni; the group's internal boundaries are still being worked out taxonomically. Despite the shared common name, Sternarchorhynchus and the rest of the Gymnotiformes are not related to the Asian featherback and clown knifefishes (Chitala, Notopterus), whose similar blade-shaped body is a case of convergent evolution, not kinship. The Catalog of Fishes is the authority for the valid name.
Morphology
Like its relatives, S. curvirostris has a laterally compressed, blade-like body tapering to a fine, whip-like tail, with no dorsal fin and no distinct caudal fin; forward and backward movement is driven almost entirely by a long anal fin run as a travelling wave along the underside of the body. The genus name itself describes the fish's most obvious feature — a long, distinctly downcurved (decurved) snout, elongated well past the mouth, that sets Sternarchorhynchus apart from blunter-snouted apteronotid genera such as Apteronotus or Sternarchella.
Running beneath the skin along most of the body is the electric organ, paired with an array of sensory pores that detect the field it generates. As in all Apteronotidae the skin is scaleless, leaving the fish with no scale armor and, by extension, no protection against the kind of medications and water-quality swings that scaled fish tolerate more readily. Specific length measurements and color pattern in life are not well documented for this species in the available literature — many Sternarchorhynchus are known chiefly from preserved museum specimens, so details such as living coloration remain data sparse.
Habitat
Sternarchorhynchus curvirostris is known from Ecuador, in the Río Putuno (a tributary of the Río Bobonoza) near its type locality of Canelos, and from the Brazilian Amazon, including the Rio Uatumã, the Paraná Afoia within the Rio Solimões system, and the Rio Negro. As with most of the genus, it is a benthic fish of lowland Amazonian river channels, living on or near the bottom in flowing, well-oxygenated water rather than in still backwaters.
Species in this genus are typically nocturnal — documented directly for the related S. goeldii — spending daylight hours sheltered near cover and becoming active after dark, when their electric sense lets them navigate and hunt in water where vision is of little use. Precise water chemistry data (temperature, pH) for S. curvirostris itself has not been reported in the literature reviewed; the genus as a whole is associated with the soft, warm, tannin-influenced river water typical of Amazonian lowland habitats.
Feeding
Sternarchorhynchus species feed on invertebrates, and their long, decurved snout is presumed to aid in probing sediment, leaf litter and crevices for hidden prey — a foraging strategy consistent with the elongated rostrum shared across the genus. As with other Apteronotidae, prey location likely relies heavily on electrolocation in the dark, detecting the faint electrical signatures of buried or hidden invertebrates rather than sight.
No specific feeding data — prey items, foraging behavior, or aquarium diet — has been documented for S. curvirostris itself in the sources reviewed; this species is essentially unknown in captivity, and what can be said here is inferred from the genus and family rather than observed directly in this species.
Mating
As in other Apteronotidae, the electric organ discharge in this family carries information beyond simple electrolocation — it functions as a social signal that can convey a fish's identity, sex and reproductive state, and courtship in related genera involves modulations of the discharge ("chirps") exchanged between individuals. Whether S. curvirostris uses its wave-type discharge in this way has not been directly studied; the point is inferred from the shared electrosensory biology of the family rather than observation of this species.
No courtship or spawning behavior has been documented for S. curvirostris specifically. Data on this species' reproductive biology is sparse to the point of being essentially absent from the literature.
Breeding
No breeding records exist for Sternarchorhynchus curvirostris. Apteronotidae in general are egg-layers but are only rarely bred in captivity; fish that do reach the trade are typically wild-caught rather than aquarium-spawned, and no substantial parental care has been documented anywhere in the family.
Given that S. curvirostris is not established in the aquarium hobby at all, there is no captive breeding history to draw on. The honest statement is that this species' reproductive mode, spawning triggers and any parental behavior remain undocumented and data sparse.
In the aquarium
Sternarchorhynchus curvirostris is not a hobby fish. It does not appear in the aquarium trade in any documented way, and the practical husbandry notes available for the genus come from a related, occasionally-traded species, S. oxyrhynchus (the elephant-nose knifefish), which is reported to reach around 15.5 in and is kept in soft, near-neutral to slightly acidic water (roughly pH 6.2–7.2) at 75–82 °F in tanks of 90 US gal or more — figures that should be read as an indication of what the genus likely needs, not as confirmed data for this species.
Any apteronotid, traded or not, is scaleless and would need the same core precautions as its relatives: no copper-based medications, reduced dosing generally, stable water quality, and dim lighting with secure cover to suit a nocturnal, electrolocating fish. Because S. curvirostris itself is essentially unknown in captivity, none of this can be stated as confirmed for the species — it is a museum-and-field fish, not an aquarium one.
Conservation
Sternarchorhynchus curvirostris is assessed by the IUCN Red List as Data Deficient, reflecting how little is known about its population size, trends and full distribution. It has been recorded from a handful of localities spanning Ecuador and the Brazilian Amazon, but the sparse sampling typical of deep-channel Amazonian electric fish makes it difficult to say more.
As with other narrow-range or poorly sampled Amazonian basin species, the general pressures facing the region — deforestation, water pollution and habitat alteration from dams and development — are the plausible long-term concerns, but no species-specific threat assessment exists for S. curvirostris beyond its Data Deficient listing. It is not part of the aquarium trade, so collection pressure is not a relevant factor for this species.