Goldfish, those innocent pets of childhood once relegated to the fish bowl, are now taking over fresh waterways around the world. A member of the carp family, the species can grow to between 16 to 19 inches and weigh more than 2 pounds in the wild.
Due to a high rate of reproduction and a lack of natural predators, goldfish easily disrupt ecosystems by consuming resources, eating eggs of native species and spreading disease. Impact examples include the recent drainage of an artificial stream in Utah to remove thousands of illegally dumped goldfish, a lake under threat from a booming population in Colorado and giant versions of the species running amok in Australia.
The species is so prevalent in the warm, shallow waters of western Lake Erie that it's now a commercial catch with over 113,800 pounds of goldfish netted in 2015.