Species that are considered uncertain risk need a more in-depth assessment beyond the Risk Summary to better define the species’ risk to U.S. environments.
Xiphophorus hellerii, Green Swordtail, is a fish native to Central America, including the countries of Belize, Guatemala, Honduras, and Mexico. It inhabits fast-flowing streams and rivers around vegetation, but can also thrive in warm springs, ponds, and ditches. This species has a wide distribution beyond its native range, with established populations in Asian, African, European, Caribbean, Oceanic, and North American countries. Within the United States, it is established, or possibly so, in Colorado, Florida, Hawaii, Idaho, Montana, Nevada, Texas, Wyoming, California, and Oklahoma. Many introductions have occurred through intentional release or escape from captivity, as this is a popular aquarium fish globally. The species has been associated with negative impacts in many locations where introduced, although its direct influence relative to other factors is unclear. It has been implicated in the decline of the Utah sucker Catostomus ardens in a thermal spring in Wyoming and the decline of native damselflies on Oahu, Hawaii. Some of these records may actually represent hybrids rather than pure X. hellerii. X. hellerii is also a carrier of numerous parasites and diseases that could negatively influence native species in nonnative waters where it is established. History of invasiveness is classified as “none documented.” The climate match to the contiguous United States was high overall. Due to the lack of clear and convincing evidence on impacts of introductions, the overall risk assessment category for Xiphophorus hellerii is uncertain.
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Uncertain Risk
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