CHICAGO — It looks like a pike on steroids. But, the northern snakehead, a non-native fish with a voracious appetite, is one fish no one wants in the neighborhood.
This week, fish biologists were alarmed to learn that a Chicago-area fisherman caught a snakehead in his net while fishing in Lake Michigan's Burnham Harbor.
"I hope this is the only one they find in Lake Michigan," Walter Courtnay, of the U.S. Geological Survey told the Chicago Tribune. "If there is a male and female out there, anything can happen."
Major threat to habitat
The snakehead is a potential threat to inland lakes and rivers because it feeds on native fish and can wipe out some species of sport fish. In the Great Lakes, they would compete with popular sport fish like bass and walleye.
Snakeheads can also survive several days out of water if they are kept wet. The fish have earned the nickname "Frankenfish" because of their ability to survive, even after extreme measures are taken to eradicate them.
There are no indications that there are other snakeheads in the same harbor, but if they are found, it's likely an eradication program would be started.
When the fish was discovered in Maryland two years ago in a pond behind a Dunkin' Donuts in Crofton, officials poisoned the entire pond. That is not a likely solution for the Great Lakes.
The lucky fisherman
Matthew Philbin of Tinley Park, Ill. was fishing for salmon over the weekend at Burnham Harbor, which is near downtown Chicago and connected to Lake Michigan. He saw an odd-looking fish.
"I was 7 or 8 feet above the water when the fish swam up toward the wall…. I honestly thought it was a northern pike.… That's clearly not what it was,” Philbin told the St. Paul Pioneer Press.
Philbin had never heard of the northern snakehead, but said the fish looked "really bizarre." What he netted was about 18 inches long with a large mouth filled with many long, sharp teeth. The native of China, Korea and Russia can grow to as much as 3 feet long.
Philbin took the creature home, took digital pictures of it and posted the images on a fishing Web site. "I said, 'Check out this fish. What is it?' It got the attention of a lot of people."
Snakeheads on the move
What troubles many wildlife experts is that the snakehead discovery in the Midwest could represent a huge new habitat with no natural defenses against the predator.
Snakeheads are reported to be so aggressive, they thrash around in aquariums when they are agitated. Federal officials prohibit importing snakeheads or their eggs into the United States.
Since they were found in the Maryland pond, biologists have found what they believe to be a reproducing population in the Potomac River in Virginia and a tributary of the Delaware River.
Illinois officials say they plan to use electric shocks to kill fish in Burnham Harbor as they search for more snakeheads, but they say the shocks only penetrate about three feet of water. Fish in the deep areas may be missed. The best scenario, they say, is that someone dumped their aquarium and the fish caught last weekend is the only one of its kind.
Maryland Department of Natural Resources biologist Steve Early fears that getting rid of the snakehead will be impossible if they spread into the Great Lakes' waterways.
"They're going to affect the food chain from the bottom up. You need to stop them before it's too late," Early told the Chicago Tribune.
Jack Chesnutt is an NBC News producer.