*Article* **A GIS Modeling Study of the Distribution of Viviparous Invasive Alien Fish Species in Eastern Europe in Terms of Global Climate Change, as Exemplified by** *Poecilia reticulata* **Peters, 1859 and** *Gambusia holbrooki* **Girarg, 1859**

**Oksana Nekrasova 1,2, Volodymyr Tytar 1, Mihails Pupins 2, Andris Ceir ˇ ans ¯ 2, Oleksii Marushchak 1,\* and Arturs Skute <sup>2</sup>**


**Abstract:** The potential distribution of tropical fish species in Eastern Europe—*Gambusia holbrooki* (introduced for biological control) and *Poecilia reticulata* (aquarium species, found in waste waters of big cities)—tend to be of particular interest in terms of global climate change. After GIS modeling of our own data and findings listed in the GBIF databases (2278 points for *G. holbrooki* and 1410 points for *P. reticulata*) using the Maxent package and 'ntbox' package in R, 18 uncorrelated variables of 35 Bioclim climatic parameters from CliMond dataset, it was found out that by 2090 guppies will appear in the south of Ukraine (Danube river's estuary, as well as in several places in the Caucasus and Turkey with habitat suitability > 0.3–0.5). *G. holbrooki* will also slightly expand its range in Europe. Limiting factors for *G. holbrooki* distribution are: bio1 (Annual mean temperature, optimum +12–+24 ◦C) and bio19 (Precipitation of coldest quarter (mm). Limiting factors for *P. reticulata* are: bio1 (optimum +14–+28 ◦C), bio4 (Temperature seasonality), bio3 (Isothermality). Unlike *G. holbrooki*, guppies prefer warmer waters. Such thermophilic fish species do not compete with the native ichthyofauna, but they can occupy niches in anthropogenically transformed habitats, playing an important role as agents of biological control.

**Keywords:** ecological niche model; distribution; aquaculture; mosquitofish; climate change; expansion
