Invasive Snakeheads Found Above Great Falls

Snakeheads Spread to Upper Potomac Waters, Threaten Native Fish

 Northern snakehead fish

First discovered in the tidal Potomac River Watershed in 2002, the northern snakehead fish from China is now spreading into the C&O Canal and the Upper Potomac River. 

Sightings and a study by the Maryland Department of Natural Resources (DNR) and US Fish & Wildlife Service validate concerns that snakeheads are gaining a foothold in upstream waters, putting at risk the native fish they feast on.

“Eradication is not possible once these fish become established in an open river system such as the Potomac,” said DNR inland fisheries biologist John Mullican.

There are competing theories to explain the presence of snakeheads in the non-tidal waters of the Potomac. The dramatic landscape of Great Falls would make it difficult for the snakehead to naturally progress directly upstream; most experts assume they would be unable to swim past this natural barrier.

Andrew Landsman, a biologist with the National Park Service, told WAMU, "More likely, it would be reintroduction by someone who wanted to recreationally fish for them. Or someone who wanted them to establish a population in order to eat them."

Experts from DNR believe snakeheads could have spread to the Potomac River by way of the C&O Canal. Sneakhead adults and juveniles have been spotted in the canal in recent years. The canal uses waste weirs, spillways, and overflow areas to regulate the level of water and mitigate flooding damage. Snakeheads may have swam through these exchanges upstream of Great Falls and reached the Upper Potomac's waters. 

Fishing pressure in the tidal Potomac River has been effective in reducing the growth of the snakehead population. 

Potomac River Anglers: Remove the river's most troublesome invasive fish!

There are no seasonal, size or creel limits for these three invasive species in Maryland: snakeheads, blue catfish, and flathead catfish. Enjoy catching and remove these fish by any legal method.

If you observe or catch an invasive fish, please report it to

More Resources

Northern Snakeheads >

Blue Catfish >

Flathead Catfish >


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