Marte Kitson

MN Sea Grant/Kevin Kapuscinski, Lake Superior State University

It was a plot (almost) worthy of a Sharknado-type movie: hundreds of goldfish inhabiting the UMD campus's Rock Pond back in 2004.

But folks dumping their unwanted aquarium fish and plants in local waters are a real-life nightmare: in addition to the cruelty of dumping fish into an environment they're not suited for, if they do survive, they and the plants become invasives who may also spread diseases.