The article goes on and states that one of these species in UK waters is a nightmare for environmentalists and conservationalists - why? What does a snakehead do? - or is because they would eat anything and everything (considering those teeth!)
Here is a video of what a snakehead can do to a similarly sized catfish.
Pretty terrifying. They are a warm fresh water fish, but they've been found farther north in American rivers than thought possible because nuclear power plants along rivers are warming the water year round.
They have a voracious appetite, and can even wiggle short distances on land to other water sources.