Taxonomy & naming
Engraulisoma taeniatum was described by Castro in 1981 and it remains the sole recognised species in the genus Engraulisoma, a monospecific placement the Catalog of Fishes (Eschmeyer, California Academy of Sciences) continues to uphold. The genus sits in the family Triportheidae, the keeled or "hatchet" characins, a group more usually associated with the deep-keeled, strong-jumping Triportheus species; Engraulisoma taeniatum is a comparatively slim, elongate outlier within that family rather than a typical hatchet-bodied member.
As a monotypic genus with a limited literature footprint, E. taeniatum has not been subject to the kind of generic reshuffling that has hit larger serrasalmid genera in recent decades. Data on this species is genuinely thin outside of the aggregator record — FishBase, IUCN and iNaturalist between them supply the bulk of what is verifiable, and this article does not go beyond what those sources state.
Morphology
FishBase records a maximum size for Engraulisoma taeniatum of just 1.5 in standard length, making it one of the smallest characins covered under the Piranhas & Pacus umbrella — a useful reminder that this group spans everything from finger-length minor characins to metre-long game fish. Its trophic level is recorded at 3.0, consistent with an intermediate consumer feeding on a mix of small invertebrates and organic material rather than at either extreme of the food web.
Detailed morphological description — body depth, fin counts, colour pattern — is not available in the cached record for this species; the family placement in Triportheidae suggests a laterally compressed, silvery body typical of small pelagic characins, but that inference should not be read as a documented fact beyond the source material.
Habitat
Engraulisoma taeniatum has a wide South American distribution for such a small fish, recorded from Bolivia, Brazil, Colombia, Ecuador, Guyana, Peru and Venezuela. FishBase lists it from the Amazon, Araguaia-Tocantins, upper Paraguay, Napo and Orinoco river basins, and iNaturalist occurrence records confirm its presence in both the Paraguay and Napo systems specifically. FishBase describes the species as freshwater and pelagic, meaning it is found in open water rather than tied closely to structure or the benthos.
No specific temperature or water-chemistry data is given in the cached sources for this species. Given its pelagic habit and the breadth of lowland Amazonian and Orinoco basins it occupies, warm, soft-to-neutral tropical river conditions are a reasonable general expectation for the group, but no pH or temperature figures are confirmed for E. taeniatum specifically, and none are stated here as fact.
Feeding
The cached record gives a trophic level of 3.0 for Engraulisoma taeniatum, placing it as an intermediate consumer — consistent with a small pelagic characin feeding on zooplankton, small invertebrates and fine organic matter in open water, in the general pattern of many small hemiodontid and minor characins in this group. No detailed dietary study or gut-content data is available in the cached sources, so specific prey items and foraging behaviour are not documented here.
Mating
No courtship or pairing behaviour is documented for Engraulisoma taeniatum in the cached sources. As a small, wide-ranging pelagic characin in a family where several relatives are open-water egg-scatterers, a broadcast-spawning pattern would not be surprising, but this is inference rather than a confirmed fact for this species, and none of the three cached sources (FishBase, IUCN, iNaturalist) report reproductive behaviour.
Breeding
There is no confirmed breeding-mode data for Engraulisoma taeniatum in the cached sources, and given how little is published on this species generally, no aquarium or aquaculture breeding record should be assumed. Consistent with the honest-reporting standard for this group: rather than defaulting to an assumed egg-scattering mode, this account states plainly that breeding biology for E. taeniatum is undocumented in the available literature. It is not known to be bred in the aquarium hobby.
In the aquarium
Engraulisoma taeniatum is essentially unknown in the aquarium trade — it carries no common name in the cached sources and no hobbyist care literature was found. At a maximum size of just 1.5 in SL it would, in principle, suit a modest species or community tank if it were ever available, standing in sharp contrast to the pacus and wolf fish elsewhere in this group that outgrow home aquaria entirely. As a pelagic characin it would likely need to be kept in a shoal in open swimming space rather than singly, in line with the general pattern for small schooling characins, but this is a reasonable expectation rather than documented care advice, since no aquarium-keeping records for this species were found in the cache.
Conservation
Engraulisoma taeniatum is assessed by the IUCN Red List as Least Concern, an assessment dated December 2020, and FishBase independently records the same LC status. The species' wide distribution across the Amazon, Araguaia-Tocantins, upper Paraguay, Napo and Orinoco basins, spanning at least seven countries, supports this rating; FishBase also notes it has low fishing vulnerability. There is no indication in the cached sources of significant trade pressure, habitat-specific threats, or population decline for this species.