Many species of Snakehead have been introduced to foreign countries where they have acquired the reputation of voracious predators that gobble up prey without being picky. And place native species under tremendous pressure. But none can rival the legend surrounding the Northern Snakehead (Channa argus). It has invaded North America, and become famous as ‘Frankenfish’. While it doesn’t quite have the man-eating credentials of the Red Bellied Piranha (Pygocentrus nattereri), it is seen doing in reality to the local fish (and small amphibians, reptiles and mammals) what the latter does to humans in B-grade Hollywood films. Add to that ferocious temperament the Snakehead’s impressive teeth, ability to survive outside water (thanks to labyrinth organs that act like lungs) and travel (a few hundred meters) overland. No wonder then that the discovery of specimens in rivers along the Atlantic seaboard triggered panic and speculation. Here’s a 2016 article from the National Geographic that sums up the mood surrounding the ‘invasion’:

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 Asia for the aquarium and seafood trades until 2004. Now they pose a risk to the embattled wildlife of the continent’s largest estuary, but people are fighting back. State officials are working with fishermen to keep the population in check and try to prevent it from spreading even farther. State and federal laws also now prohibit keeping or transport of live snakeheads.

Northern Snakeheads hail from East Asia (the Russian Far East, Korea and China). The first sighting in the USA (unconfirmed) was in the state of California (on the Pacific shore) in 1997. From then on, individuals have been seen in the waterways along the eastern coast, from Maryland in the north to Florida in the south. Another region of the continental United States invaded by them is Lake Michigan. Their ravenous appetite and unusual habits have made them a favorite of the media. In 2004, the American cable and satellite television channel, SyFy (or Sci Fi, famous for series like ‘Battlestar Galactica’ and ‘Taken’), produced two films – ‘Snakehead Terror’ and ‘Frankenfish’, inspired by the furore surrounding the discovery of the species in a pond, in Crofton, Maryland. This was followed by Ten Pound Films’ ‘Swarm of the Snakehead’ in 2006. Reproduced below is an excerpt from Smithsonian describing the paranoia:

The culprit in the Sci Fi Channel’s made-for-TV movie Snakehead Terror turns out to be a lakeful of monster fish. This star turn is fitting for the toothy “Frankenfish” that has generated many hair-raising newspaper and television news stories—the northern snakehead. It was after another angler caught a snakehead in the same pond and netted some babies that all hell broke loose. National newspaper and TV news reports described snakeheads as vicious predators that would eat every fish in a pond, then waddle across land to another body of water and clean it out. A reporter from the Baltimore Sun called it “a companion for the Creature from the Black Lagoon.” The scariest reports, fortunately, turned out to be mistaken. While some species of snakeheads can indeed wriggle long distances across the ground, the northern snakehead—the only species found in the Crofton pond—appears not to be one of them. But northern snakeheads do like to eat other fish, and a heavy rain could conceivably wash one or more from the pond into a nearby river that runs through a National Wildlife Refuge and into the Chesapeake Bay, the largest estuary in North America. To eliminate the snakehead menace, Maryland wildlife officials dumped the pesticide rotenone into the Crofton pond, killing all of its fish. Six adult snakeheads went belly up—as did more than 1,000 juveniles. Problem solved. Or so it appeared.

Two years later, northern snakeheads fulfilled biologists’ worst fear and showed up in the Potomac River. Experts worried that snakeheads in the Potomac, by eating other fish or out-competing them for food, could drive down numbers of more desirable species, such as shad or largemouth bass. You can dump poison in a little, enclosed pond, but you can’t poison the Potomac. It’s a wide, shallow river that originates in West Virginia and runs 380 miles before emptying into the Chesapeake. The bay fuels the region’s economy through recreation and fishing. Snakeheads couldn’t survive in the mildly salty water of the bay, but they could scarf down shad, fish that spawn in the Potomac and other freshwater tributaries. Millions of dollars have already been spent on fish stocking, dam modifications and other projects to help the shad, which used to be plentiful enough to support a commercial fishery in the bay.

Besides Crofton and the Potomac, the fish have popped up in several other places in the United States. In 1997, one was caught in a Southern California lake. A couple more appeared in Florida waters in 2000. In Massachusetts, one was caught in 2001 and a second in 2004. And in July 2004, an angler caught two in a lake in a Philadelphia park. Like the Crofton fish, the Philadelphia ones had settled in and started reproducing. But unlike the Crofton fish, they had access to a river—the Schuylkill, which feeds into the Delaware. Moreover, tidal gates that normally keep fish in the park had been stuck open for two years. Philadelphia fisheries managers decided that poisoning or draining the park’s interconnected ponds would cause more harm to resident fish than the snakeheads would, and have resigned themselves to snakeheads becoming a new member of the park’s ecosystem. The most recent surprise appearance was this past October when a northern snakehead was pulled out of Lake Michigan. The catch has raised fears that the voracious predator might take over the Great Lakes.

Image Attribution: The image above from Wikimedia Commons, is taken from an illustration in the book ‘Histoire Naturelle des Poissons’ published by the French naturalists Georges Cuvier (1769-1832), and Achille Valenciennes (1794-1865) between 1828 and 1849. It shows a Great Snakehead (Channa marulius), another species of the genus Channa that has also established itself as an invasive species in the USA.