When snakeheads were first discovered in a pond in Maryland in 2002, the public panicked. People feared the big, voracious Asian fish would gobble up native species and take over local waterways. Since then, those fears have proven to be only partially correct.
The northern snakehead has established itself firmly in the Potomac River system, with a population estimated at somewhere above 21,000 individuals, ranging through more than 120 river miles (200 kilometers). Growing up to 18 pounds (8 kilograms) and three feet (one meter) long, the "Frankenfish" keep spreading; they have recently been found above Great Falls in the C&O Canal (north of Washington, D.C.), as well as in the upper Chesapeake Bay.
The invasive species were imported legally from