Orestias ascotanensis is seen as one of the many synonymes of Orestias agassizii.

Orestias ascotanensis is a killifish endemic to the Ascotán salt pan in the Chilean Altiplano, where it inhabits 12 springs with different degrees of isolation. This species is a suitable model for studying the effect of serial geographical isolations on the differentiation process among populations. The present study examines the genetic variation and structure of the species using mitochondrial DNA control region sequences and eight microsatellite loci, analyzing populations across its distribution range. The evaluation of genetic variation revealed high levels of diversity within the species. The genetic structure analysis showed the existence of four differentiated groups: two groups were formed by the springs located in the northern and southern extremes of the salt pan and two groups were found in the centre of the salt pan. The latter two groups were formed by several springs, most likely as a consequence of the South American summer monsoon that could connect them and allow gene flow. The patterns of genetic differentiation appear to be determined based on the physical isolation of the populations. This isolation may be the result of a combination of factors, including geographical distance, a historical decrease in water levels and altitude differences in the springs of the salt pan. Therefore, this system is a rare example in which hydrological factors can explain genetic differentiation on a very small scale. Cited from: Franco Cruz-Jofré et al, 2016

Members of this genus have been generally maintained and bred only under controlled laboratory conditions rather than as aquarium fishes. Therefore, information about maintainance and breeding is present here as part of the general information about the genus rather than under each individual species. This information is based mainly on that obtained in the laboratory of the zoological Institute and zoological Museum, Hamburg (Villwock, 1995b)

Keeping and breeding Orestias species in captivity requires that the water is relative cool with temperatures between 10 and 15 C. Optimal water temperatures would be about 13 C.

Today it is believed that the species from the genus Orestias reach sexual maturity when they still display juvenile coloration and morphology. At that stage it is very difficult to recognise the sexes.

Eggs are deposited one by one or in a small cluster in fine substrate like live plants with fine leaves. Development of the eggs takes about 4 weeks due to the low temperatures the eggs should be stored. Youngs grow slow and can be fed by artemia nauplii and small worms and crustaceans

Remarks :

Because this special treatment the genus Orestias is seldom found in the tanks of hobbyists.

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Franco Cruz-Jofré, Pamela Morales, Irma Vila, Yareli Esquer-Garrigos, Bernard Hugueny, Philippe Gaubert, Elie Poulin, Marco A. Méndez. 2016. Geographical isolation and genetic differentiation: the case of Orestias ascotanensis (Teleostei: Cyprinodontidae), an Andean killifish inhabiting a highland salt pan. Biological Journal of the Linnean Society, Volume 117, Issue 4, April 2016, Pages 747–759, https://doi.org/10.1111/bij.12704

Morales, P., Gajardo, F., Valdivieso, C. et al. Genomes of the Orestias pupfish from the Andean Altiplano shed light on their evolutionary history and phylogenetic relationships within Cyprinodontiformes. BMC Genomics 25, 614 (2024).

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