Blue tilapia, a now popular food item, has escaped aquaculture operations in North Carolina, Oklahoma, Pennsylvania, Colorado, and Texas where they were collected in open waters in each of the states.  I’ve seen what this species can do in Florida lakes by totally dominating other species in biomass.  The Mozambique tilapia, believe it or not, can be found in several geothermal springs and effluents in Idaho and is considered a pest around the world. It has been established here in Florida since the 1960s.  Both of these fishes were also stocked for biocontrol of aquatic weeds.  I want to add that many small, tropical aquarium species such as mollies and guppies have also been collected from geothermal springs of the West.