Taxonomy & naming
Parastremma sadina was formally described by Carl H. Eigenmann in 1912. Eigenmann was a prolific American ichthyologist responsible for a large portion of the early systematic work on South American characids, and several of his 1912 contributions drew on material collected from rivers of northern and western South America. The genus Parastremma is a small characin genus within the family Characidae; published information on how many valid species it currently contains and where it sits within the broader characid phylogeny is sparse in sources available to this account.
The specific epithet sadina is a Latin or Latinised word meaning sardine or sardine-like, likely an allusion to the general body form of the type specimen. Eschmeyer's Catalog of Fishes (CAS) is the governing authority for the valid name; the combination Parastremma sadina Eigenmann, 1912 is the name as recorded there. No synonyms or subsequent reclassifications are noted in publicly available sources consulted for this account.
Morphology
Detailed morphological data for Parastremma sadina are not available in publicly accessible sources consulted for this account. As a member of the family Characidae, it is presumed to be a small, laterally compressed freshwater fish with the adipose fin typical of the family, but no published measurements of standard length, fin-ray counts, or scale counts have been located.
Data sparse: size, colouration, and meristic characters cannot be reported with confidence for this species at this time.
Habitat
The type locality for Parastremma sadina, as recorded in Eigenmann's original description, is Istmina in western Colombia, placing the species in Colombia's Pacific-slope drainages. The species has not been recorded from citizen-science occurrence databases in any quantity that would allow a reliable range statement to be made here.
Data sparse: water-chemistry parameters, habitat type, and confirmed distribution cannot be reported without risk of fabrication.
Feeding
No published dietary information is available for Parastremma sadina. Small Neotropical characids of this body type are generally opportunistic feeders on small invertebrates, zooplankton, and organic particles, but applying that generalisation to this species specifically would be speculative.
Data sparse: feeding ecology has not been studied or documented in accessible literature.
Mating
No observations of mating behaviour have been published for Parastremma sadina. The species has not been recorded in the aquarium hobby literature and is unknown in captivity, so field and captive behavioural data alike are absent.
Small Neotropical characids broadly show egg-scattering open-water or plant-associated spawning with no parental care, but this cannot be confirmed as applying specifically to Parastremma sadina without primary documentation.
Breeding
No breeding data are available for Parastremma sadina. The species has never been maintained or bred in captivity to this author's knowledge, and no field accounts of spawning have been published in sources consulted here.
Data sparse: clutch size, incubation period, egg type, and spawning mode are unknown and cannot be responsibly reported.
In the aquarium
Parastremma sadina is not known in the ornamental-fish trade and has no recorded history in the aquarium hobby. No husbandry guidelines, compatibility notes, or captive-care accounts have been published.
Data sparse: this species cannot be recommended or described as an aquarium subject on the basis of available information.
Conservation
Parastremma sadina has not been assessed by the IUCN Red List and carries no formal conservation status. The absence of an assessment reflects the broader obscurity of the species: no population surveys, range estimates, or threat analyses appear to have been published.
Until the species receives a formal assessment and its distribution is better documented, nothing reliable can be said about whether it faces habitat pressure, over-collection, or range contraction. It is one of many Neotropical characids whose conservation standing remains entirely unknown.