Taxonomy & naming
Poecilia koperi was described by F.N. Poeser in 2003 as part of the long, unfinished work of untangling the South American mollies of the genus Poecilia. The genus is large and taxonomically turbulent — its members range from the familiar guppies and sailfin mollies to a cloud of small, similar, regionally restricted species whose limits have been repeatedly revised — and koperi is one of the forms separated out as that revision proceeded. Eschmeyer's Catalog of Fishes treats Poecilia koperi Poeser, 2003 as the valid name and the governing authority for the species, placing it in the genus Poecilia within the subfamily Poeciliinae of the family Poeciliidae, the New World livebearers, in the order Cyprinodontiformes.
The family Poeciliidae unites the guppies, mollies, platies, swordtails, mosquitofishes and their relatives — small, internally fertilising, predominantly live-bearing toothcarps of the Americas. Within that family Poecilia is the molly genus, and koperi sits among the South American members rather than the better-known Central American sailfins of the hobby. The species epithet is an eponym: the fish was named for Michel Koper, a friend of the describing author Poeser. The common name on record, "Curipe Toothcarp," points to a Venezuelan locality, but no widely used vernacular name exists because the species is unknown in the aquarium trade.
Morphology
Detailed published morphology for Poecilia koperi is sparse. As a member of Poecilia it is a small, laterally compressed livebearer of the general molly build — a stocky-bodied, small-scaled toothcarp rather than the elongate, colour-spotted form of a guppy — but FishBase carries no maximum-length figure, no maturity size, and no fin-count or coloration summary for the species, so any precise measurement would be a guess rather than a record. The single quantitative datum available is a Bayesian length–weight relationship (a = 0.00851, b = 3.15), a modelled value estimated from the species' body form and its relatives rather than a direct measurement of koperi itself.
In keeping with the genus, the species is expected to show the standard poeciliid sexual dimorphism: males bearing a gonopodium — the intromittent organ formed from modified anal-fin rays that defines the live-bearing toothcarps — and females being larger and deeper-bodied, particularly when gravid. The strength of any colour difference between the sexes is not documented for koperi. Because no koperi-specific description of adult size or coloration has been compiled in the accessible references, the safest statement is that the species' morphology is data-sparse beyond its placement as a small South American molly.
Habitat
Poecilia koperi is a freshwater fish of tropical South America, recorded from Venezuela. FishBase classifies it as a benthopelagic freshwater species — one that lives in association with the bottom but ranges up into the open water column — in a tropical climate, which is consistent with the small lowland streams, pools and slow margins typical of the genus's South American members. The IUCN assessment lists Venezuela (Bolivarian Republic of) as the only range country and places the species in inland fresh waters, but does not populate specific localities or depth limits, and the common name "Curipe Toothcarp" is the closest the record comes to a named site.
Beyond country and broad habitat type, the species' ecological envelope is essentially undocumented in the accessible sources: no temperature range, pH, hardness or depth figures have been published for koperi specifically. Inferences could be drawn from the warm, neutral-to-alkaline lowland waters that South American mollies generally occupy, but no measured environmental data exist for this species, and the honest position is that its habitat is known only at the coarse scale of "tropical fresh waters of Venezuela."
Feeding
No diet study or stomach-content analysis has been published for Poecilia koperi, and FishBase carries only a modelled estimate — a trophic level of about 2.6, derived from the species' size and its relatives rather than from direct observation. A figure in that range indicates a low-level omnivore, which matches the general feeding ecology of mollies: opportunistic grazers and micro-predators that take algae, biofilm and detritus together with small aquatic invertebrates and whatever drifting items they can capture.
In the absence of any koperi-specific feeding record, the responsible summary is that the species is presumed to be an omnivore in the molly mould, leaning toward algal and detrital grazing supplemented by small invertebrate prey, with the actual balance of plant to animal matter unrecorded. Because the fish is not kept in aquaria, there is likewise no captive-feeding experience to draw on. Its feeding ecology should be treated as inferred from the genus, not as established for the species.
Mating
Like all poeciliids, Poecilia koperi reproduces by internal fertilisation. In these fishes the male's anal fin is modified into a gonopodium — a mobile, rod-like intromittent organ built from elongated and specialised fin rays — which he uses to transfer sperm directly to the female; there is no external egg-laying and no spawning site. Females of many poeciliids can store viable sperm internally for extended periods, allowing a single mating to fertilise several successive broods, and male mollies typically combine display-based courtship with persistent pursuit of receptive females.
None of the specifics of this behaviour have been documented for koperi: there are no published observations of its courtship, no data on mate choice, and no description of how conspicuous or persistent its males are. What can be said is constrained to the genus level — that fertilisation is internal and mediated by the gonopodium, and that the molly pattern of continuous, store-and-reuse reproduction almost certainly applies. The species' own mating behaviour is, on the present record, undescribed.
Breeding
Poecilia koperi is a livebearer: as a member of Poecilia it is viviparous, the female carrying developing embryos internally and giving birth to free-swimming young rather than laying eggs. Across the genus the nutritional strategy spans a lecithotrophic-to-modestly-matrotrophic range — the embryos are nourished mainly by yolk, sometimes with limited maternal provisioning during gestation — but the position of koperi on that spectrum has not been measured. FishBase populates no reproductive data for the species at all: no gestation period, no brood size, and no information on whether it shows superfetation, the capacity of some poeciliids to carry overlapping broods at different developmental stages simultaneously.
Because the species is an obscure Venezuelan form with no presence in the aquarium hobby, there is also no captive breeding experience to fill the gap. The most that can be stated with confidence is that koperi gives live birth via internal fertilisation, in the manner universal to the family; gestation length, fecundity, brood frequency and any superfetation are all data-sparse and should not be assigned numbers. Where guppy or sailfin-molly figures might be borrowed, they would be assumptions about a relative rather than records of this fish.
In the aquarium
Poecilia koperi is effectively absent from the aquarium hobby. No dedicated livebearer or aquarium-care source for the species could be located; searches surface only generic Poecilia and molly care pages built around the familiar trade species — sailfin and black mollies, the guppy, Poecilia caucana, Poecilia orri — and none of them concern koperi. It is an obscure Venezuelan endemic that is not collected for, established in, or bred within the ornamental trade.
As a result there is no body of husbandry experience to report: no recommended tank size, water parameters, temperament notes, tankmate guidance or care rating specific to this fish. Any care advice would amount to transplanting general molly husbandry — warm, hard, well-filtered water and a livebearer's appetite for algae and small foods — onto a species nobody appears to keep, which would misrepresent inference as instruction. For an atlas the accurate entry is simply that koperi is a wild species without an aquarium track record, and its captive requirements are unknown.
Conservation
Poecilia koperi is assessed as Least Concern on the IUCN Red List. The assessment was carried out on 1 March 2007 and published in 2009 (assessment 167754/6377203), and the species was confirmed at Least Concern in the most recent Red List version. The rationale is straightforward: the species was judged Least Concern because no threats are acting on this common fish, a conclusion reached through the freshwater fish evaluation process for the region.
The assessment treats koperi as a common, widespread-enough Venezuelan freshwater species with no identified pressures on its populations, which is consistent with FishBase's modelled profile of high resilience — a short estimated population-doubling time of under fifteen months — and low vulnerability to fishing. There is no indication of habitat loss, harvest, or other decline associated with the species. As with the wider genus, the practical conservation note is not about protecting koperi from the hobby but the reverse: because it is not in the trade, it poses none of the invasive-release concerns attached to its more familiar molly and guppy relatives, and the species' status is best described as secure but under-studied.