Taxonomy & naming
Curimatopsis jaci was described by Melo and Oliveira in 2017 as one of three new Curimatopsis species published together in the Journal of Fish Biology ("Three new species of Curimatopsis (Characiformes: Curimatidae) from the Amazon basin"). The holotype is a female, MZUSP 121197, 1 in standard length, with a paratype male measuring 1.5 in SL. It sits within the Curimatopsis macrolepis species complex and is distinguished from its congeners chiefly by details of body pigmentation.
The genus Curimatopsis belongs to the family Curimatidae within the order Characiformes — the toothless detritivorous characins, a group entirely distinct from the predatory piranhas and the plant-grazing silver dollars that share this section of the atlas. The species epithet honours Jaci, the Tupí (Yacy) lunar goddess, a name the authors chose in tribute to the senior author's mother, Maria Jaci Petrini de Melo. As a species described in 2017, its taxonomic placement has not been revised and there are no synonyms or older combinations to note.
Morphology
This is a genuinely tiny fish. The type series tops out at 1.5 in standard length (roughly 1.5 in total length), placing Curimatopsis jaci among the smallest characiforms known — smaller than most tetras kept in the hobby and well under half the size of a typical Corydoras. Like every member of Curimatidae, it is toothless: the family's defining feature is a mouth adapted for grazing rather than biting, with the jaws lacking the teeth that characterise most other characins, including the piranhas and pacus elsewhere in this atlas.
Beyond the type description's pigmentation details — the character used to separate it from its closest Curimatopsis relatives — published morphological data for this species is limited to the original 2017 paper. No detailed account of live colouration, fin shape or body proportions beyond the holotype measurements has surfaced in the sources available for this profile.
Habitat
Curimatopsis jaci is known from the Rio Cristalino, a tributary of the Rio São Benedito, itself a tributary of the Rio Teles Pires within the upper Rio Tapajós basin in the Brazilian Amazon. Its known range is narrow — the species appears to be a Tapajós-basin endemic, consistent with the pattern seen in its congeners described in the same 2017 paper.
Specific water chemistry data for this exact locality was not captured in the sources available for this profile. As a small-bodied Curimatidae species from an upper-Tapajós tributary, it can be expected to occupy warm, typically soft, Amazonian stream conditions, but that inference should not be mistaken for measured data — none is available for this species specifically.
Feeding
Curimatidae as a family are strict detritivores: the mouth is toothless and adapted to grazing decaying organic material, biofilm and fine detritus from riverbed sediment rather than pursuing prey or browsing plants. Curimatids are collectively among the dominant fish groups in Amazon basin food webs by this route, with detritus-feeding curimatids reported to make up a substantial share of fish biomass in some Amazon rivers.
No aquarium feeding trials exist for Curimatopsis jaci specifically, since the species has no known aquarium history. Based on the family's documented biology, a diet of soft sinking foods — fine flake, crushed pellets, and small live foods such as Artemia nauplii or cyclops — would suit its toothless, detritivore feeding mode, but this is an inference from family-level biology rather than a tested recommendation.
Mating
No courtship or spawning behaviour has been documented for Curimatopsis jaci. The species was described from a small type series collected in the wild — a holotype female and a paratype male — and nothing in the available literature addresses breeding condition, pairing behaviour or sexual dimorphism beyond that basic sex identification of the two type specimens. Data sparse.
Breeding
There is no record of Curimatopsis jaci being bred in captivity, and no field data on its reproductive biology beyond the collection of a holotype and a single paratype. This is consistent with the species' complete absence from the aquarium trade: it was described from scientific collecting, not aquarium stock, and nothing in the sources reviewed for this profile documents spawning behaviour, egg type or parental care for this species or, specifically, for the genus Curimatopsis. Prospective breeding mode should not be assumed from other characin groups in this atlas — it is genuinely unknown for this species.
In the aquarium
Curimatopsis jaci has no aquarium history. It was described in 2017 from scientific collections in a remote upper-Tapajós tributary, and nothing in the sources reviewed for this profile — including a 2017 hobby-press summary of the same batch of new Curimatopsis descriptions — indicates the species has entered the trade. That same coverage describes a related new species, C. maculosa (1 in SL), as "small, somewhat nondescript-looking," and notes that fish this diminutive are unlikely aquarium prospects; the same logic applies to C. jaci, whose adult size of roughly 1.5 in SL is smaller still than many established nano fish.
Were it ever to appear in the hobby, its toothless detritivore biology and minute size would call for a soft-substrate, densely planted nano setup among very peaceful tankmates — but this is speculation extrapolated from Curimatidae family biology, not a tested care regimen. There is no husbandry record to draw on.
Conservation
Curimatopsis jaci has not been formally assessed by the IUCN Red List; no assessment for this species was located. As a species described only in 2017 from a narrow, single-tributary range in the upper Rio Tapajós, it is reasonable to expect an eventual Data Deficient or Not Evaluated status pending further survey work, but no such assessment currently exists, and this profile does not assign one that has not been made.
The upper Tapajós basin, like much of the southern Amazon, faces pressure from deforestation, agricultural expansion and hydroelectric development, but no species-specific conservation data or population trend information for C. jaci was found in the sources reviewed here.