Officials Search For Invasive Species Lurking In Philadelphia Waterways

PHILADELPHIA (CBS) -- They're called the Northern snake-head fish. They're an invasive species lurking in some of Philadelphia's waterways.

Angelo Martinez fishes at the lakes at FDR Park in South Philadelphia almost every day. He catches fish like bass, cat fish, perch and northern snake-head fish.

"They are vicious. They are in here killing off everything. I caught one in here three days ago. It was a pound and a half," Martinez said.

Scientist David Keller works in the Fisheries Department of the Academy of Natural Sciences at Drexel University. He says the fish native to parts of China, Korea and Russia can grow up to two feet and are potentially a threat to this regions ecosystem.

"This is another predator that is going to be applying pressure," Keller said. "They are now competing with other animals in the area, and that is going to have that domino effect, that ripple effect, through the entire food web and the entire food chain."

The Academy of Natural Sciences will hold an electro-fishing event at the lakes at FDR Park on July 18th, removing a sampling of the fish to hope to learn more about what they are eating and how intrusive they are.