Risk Screen of Freshwater Tropical Ornamental Fishes for the Conterminous United States

The trade in ornamental fish is increasingly viewed as a major source for the introduction of invasive species into the environment. However, few ornamental fishes are established and widespread in the conterminous United States, and fewer still are thought to cause noticeable environmental impacts. To better evaluate the risk of this pathway, we conducted a risk screen of 34 important freshwater ornamental fish species by using the Fish Invasiveness Screening Kit (FISK) version 2 for the conterminous United States. Screens from three to five independent assessors resulted in categorization of 91–100% of the species as noninvasive. The low climate match of these mostly tropical species largely confines establishment risk to subtropical regions, primarily peninsular Florida, and to isolated thermal refuges (e.g., geothermal springs) in otherwise unsuitable climates. Few data on impacts exist for tropical ornamental fish in the conterminous United States, and there is little evidence for the occurrence of large, long-term effects despite local impacts for a few species. Our results indicate that the freshwater tropical ornamental fish trade is less risky to the conterminous United States than has been concluded in most previous studies. Further risk assessment for management decisions might be required on a regional scale or for localized, high-risk situations. Received November 3, 2016; accepted March 23, 2017 Published online July 18, 2017