On Wednesday, scientists and students with Drexel University went electro-fishing in Franklin Delano Roosevelt Park's Meadow Lake for northern snakehead. The technique uses electric currents to stun and study the fish population.
The problem in the Delaware Valley is that no other fish are hunting them.
"They're a top predator they're gonna do well here," says Paul Overbeck, a fisheries biologist with the Academy of Natural Sciences.
The northern snakeheads are affecting the number of popular fish life, including wide-mouth bass and carp.
David Keller, a fisheries biologist, said other species of snakhead fish "can use their pectoral fins to look like they're walking across wet vegetation."
"That's how they can get from one pond to another," said Keller.
But Keller says northern snakeheads do not have that ability.
What’s for dinner? 😳— Maggie Kent (@MaggieKent6abc) November 20, 2019
This fish is an invasive species taking over our PA/DE waterways.. although some eat it, it’s predatory nature lends to it being full of contaminants. More on the studies surrounding the Snake Head Fish on @6abc pic.twitter.com/Tuj5vvPbBU
There are a few urban legends attached to the snakehead.
Overbeck said a man once told him his dog was bitten while swimming in the water and had to have its leg amputated.
"There's not a lot of things that would bite a dog in its leg other than maybe a snakehead. I don't know if its urban legend, that was a story I heard from a gentleman and I tend to believe it," said Overbeck.
Local fishermen say despite preying on fish natural to our habitat, northern snakeheads make for an exciting game.
"They're very fierce, they jump pretty good and they put up a fight well...they do give some action. That's probably why people like them," said Gregory Price, of Smyrna, who has been fishing in the area for more than 40 years.
Anyone who catches a northern snakhead should not return it to the water.
"The state of Pennsylvania does not want you to return the fish to the waterbody you caught it from. You're supposed to kill the fish," said Keller.