<\/p>\n
Members of the order Cyprinodontiformes are cosmopolitan in\u00a0tropical and temperate latitudes, widely distributed in freshwater\u00a0and saline habitats (Rosen & Bailey, 1963). In this order, the family\u00a0Poeciliidae comprises 42 genera with about 353 species (Nelson,\u00a0Grande, & Wilson, 2016), which are small and laterally compressed\u00a0fishes, with body form ranging from extremely elongated (e.g.,\u00a0Tomeurus) to deep\u2010bodied (e.g., Phallichthys, Carlhubbsia) (Lucinda,
\n2003). Some species have been introduced in many countries by ornamental\u00a0aquarists (Magalh\u00e3es & Jacobi, 2017), and as an alternative\u00a0measure to biological control of mosquitoes (Azevedo\u2010Santos, Vitule,\u00a0Pelicice, & Garc\u00eda\u2010berthou, 2016). Seven species were already registered\u00a0in Brazilian headwater streams (Magalh\u00e3es & Jacobi, 2017).\u00a0The main introduction vector of Poecilids in Brazil is the aquarium\u00a0hobby, a practice that has gained popularity because of the ease in\u00a0obtaining a diversity of attractive species. However, certain difficulties\u00a0in the care of ornamental fish, such as the excessive growth and\u00a0aggressiveness of some species, motivate the aquarists to release\u00a0their unwanted fishes into artificial or natural aquatic environments\u00a0(Magalh\u00e3es & Jacobi, 2013). This illegal release has introduced not\u00a0only Poecilia reticulata Peters, 1859 into Brazilian streams, but also\u00a0some species of Xiphophorus (Magalh\u00e3es & Jacobi, 2017).<\/p>\n
The drainage area of the Iguazu River Basin cross different geological\u00a0and geomorphological units (Parolin, Ribeiro, & Leandrini,\u00a02010). It has many waterfalls, most notably the Iguazu Falls (82 m\u00a0high), formed in a geological event dating from the Cretaceous period\u00a0(Parolin et al., 2010), and which likely generated a cladogenic\u00a0event for many fish species in the Iguazu River. These waterfalls,\u00a0located near the mouth of this river, are classified as level\u2010three barriers\u00a0for the movement of fish, promoting the isolation of the fish\u00a0fauna. Additionally, there are more six artificial barriers along the\u00a0Iguazu River (Baixo Igua\u00e7u, 2019; Baumgartner et al., 2012). The\u00a0presence of these barriers ensures that the species do not colonize\u00a0other regions, unless they are aided by human intervention (Rahel,\u00a02007). Such geographical isolation guaranteed to the Iguazu River\u00a0Basin a small\u2010sized fish fauna, highly endemic (Baumgartner et al.,\u00a02012), and therefore a global biodiversity ecoregion (Abell et al.,\u00a02008; Hales & Petry, 2015). This basin is particularly vulnerable to\u00a0non\u2010native fish introductions, however, a recent study showed that\u00a027 fish species have already been introduced in the Iguazu River\u00a0Basin (Gubiani et al., 2018). Such introductions cause negative impacts\u00a0on endemic fish fauna, increasing the risk of extinctions (Daga,\u00a0Debona, Abilhoa, Gubiani, & Vitule, 2016; Gubiani et al., 2018).<\/p>\n
Link:\u00a0https:\/\/onlinelibrary.wiley.com\/doi\/full\/10.1111\/jai.13965<\/a><\/p>\n
![\"\"](\"https:\/\/www.ufrgs.br\/ictio\/wp-content\/uploads\/2019\/10\/501.jpg\")
<\/a>![\"\"](\"https:\/\/www.ufrgs.br\/ictio\/wp-content\/uploads\/2019\/10\/500.jpg\")
<\/a>