Taxonomy & naming
Stomatorhinus schoutedeni was described by the Belgian ichthyologist Max Poll in 1945, in a paper that revised the genus Stomatorhinus alongside several new characids from the Belgian Congo ("Descriptions de Mormyridae et de Characidae nouveaux du Congo belge avec une étude du genre Stomatorhinus et des genres de Characidae nains africains"). It belongs to the family Mormyridae — the elephantnoses and mormyrids — within the order Osteoglossiformes, the bonytongue fishes, one of the oldest surviving lineages of teleosts, named for a bony, toothed structure on the tongue that bites against toothed plates on the roof of the mouth. The species is treated as valid, but its type locality and any synonymy have not been located in the sources reviewed for this account.
The genus Stomatorhinus was erected by George Albert Boulenger in 1898 for a group of small, blunt-snouted Congo basin mormyrids, distinguished by a small mouth set low and near the tip of the snout rather than on an elongated chin barbel. Poll, who dominated mid-twentieth-century work on Congo basin fishes, added several species to the genus in his 1945 revision and afterward, and Stomatorhinus now holds close to twenty recognized species. The epithet honors Henri Schouteden, a Belgian zoologist credited with collecting the type material in the Belgian Congo.
Morphology
No maximum length has been published specifically for Stomatorhinus schoutedeni. Congeners in the genus are among the smallest mormyrids in the family, mostly maturing under about 4 in standard length, and nothing in the sources reviewed here suggests this species runs larger. Poll's description singled out the eye as the character separating it from its relatives — comparatively large, at roughly a fifth of head length and about two-thirds of interorbital width — which would be one of the more usable field marks for the species if it could be observed in life.
As in other Stomatorhinus, the body is presumably compact and laterally compressed, with a small, inferior mouth close to the tip of a short, unproduced snout rather than the elongated chin appendage — the schnauzenorgan — of the related genus Gnathonemus. Like every mormyrid it carries a weak, pulse-type electric organ near the base of the tail, read through electroreceptors spread across the skin and used to navigate and locate prey in dark or turbid water. No electric organ discharge waveform specific to this species has been published.
Habitat
Stomatorhinus schoutedeni is endemic to the Democratic Republic of the Congo, recorded within the Congo River system; freshwater fish checklists for the country include it among the basin's described mormyrids. A more specific river, tributary, or locality record has not been located in the sources reviewed for this account, and while the species is presumed to range more widely across the Congo basin, that broader distribution is inferred rather than confirmed.
Congeners in Stomatorhinus generally occupy soft, slow-moving or still tropical forest water — shaded streams, flooded forest margins, and swamp habitat rich in leaf litter and submerged root cover — the kind of low-visibility setting where an electric sense outperforms eyesight. That is a genus-level generalization rather than a measurement taken for this species, and water temperature and chemistry data specific to S. schoutedeni are not documented.
Feeding
No diet study specific to Stomatorhinus schoutedeni has been located. Mormyrids as a group are bottom-foraging invertebrate feeders, using electrolocation to find insect larvae, worms, and small crustaceans hidden in mud, silt, and leaf litter before taking them with a quick strike of the small, downturned mouth. This species is presumed to feed the same way, though that has not been confirmed specifically for it.
Mating
Courtship and mating behavior have not been described for Stomatorhinus schoutedeni. In mormyrids generally, the electric organ discharge is thought to carry more than navigational information — its pulse pattern is species-specific and, in some studied genera, sex-specific as well, with a likely role in mate recognition and shoal cohesion. Whether that holds for this species is unknown; no courtship study has been located, and nothing should be assumed from better-studied relatives.
Breeding
There is no published record of Stomatorhinus schoutedeni breeding, in the wild or in captivity. Spawning behavior, egg or larval description, and parental care are all unrecorded for this species. Breeding biology across Mormyridae is poorly documented even in well-studied genus members, and for a species with this little published natural history, a specific account of its reproduction would be invention rather than fact.
In the aquarium
Stomatorhinus schoutedeni has no documented presence in the aquarium hobby; no keeping reports, husbandry notes, or import records specific to this species were found in the sources reviewed here. What follows describes general practice for small mormyrids rather than any track record established for this particular fish.
Mormyrids as a group need a soft, fine substrate they can probe with the mouth, ample cover, dim lighting, and stable, clean water with low turbidity; the family is also known for unusual sensitivity to a number of common aquarium medications and to poor water quality, which argues for cautious acclimation and conservative dosing whenever a mormyrid needs treatment. They typically refuse dry foods and need live or frozen invertebrate foods such as bloodworm and brine shrimp, offered after the lights dim to suit their nocturnal foraging habit. None of this has been verified specifically for Stomatorhinus schoutedeni, but it reflects standard practice across the family it belongs to.
Conservation
The IUCN Red List assesses Stomatorhinus schoutedeni as Data Deficient, based on a 2020 assessment. A Data Deficient rating reflects a lack of adequate information to judge extinction risk rather than a level of risk itself — a fitting status for a species endemic to a single country and known mainly from its original description and basin-level checklists.
No population trend, range size, or specific threat is documented for this species. Broader pressures on Congo basin freshwater habitat — deforestation, siltation, and localized pollution — are the kind of long-term concern that could affect a poorly known, single-country endemic like this one, but no such threat has been documented specifically for Stomatorhinus schoutedeni, and none is asserted here.