Fish that fly; even leap into boats.
The fish, Asian carp, can launch like torpedoes when startled by motor noise. It can be dangerous.
"I've got a buddy of mine that got hit in the head less than a couple of weeks ago and knocked him out cold in the boat," says Craig Sondker, a commercial fisherman.
Their antics may be entertaining, but as CBS News Correspondent Bob McNamara reports, their exploding numbers trouble the waters of the Mississippi and Illinois rivers.
"We don't have at the moment any good way to control their numbers," says John Chick, of the Illinois natural history survey. "As far as we can tell, they're here to stay."
On good intentions, Asian carp were brought to this country two decades ago to clear alge and parasites from the Arkansas and Mississippi ponds that grow catfish. But when floods came in 1993, the carp escaped into the Mississippi River.
"I don't see any way of stopping it," says Lance Gregorson, a commercial fisherman. "I'd say it's just going to get worse."
Gregorson and fellow fisherman Stanley Briney say the invading carp that clog and tear their Illinois River nets have driven off the Buffalo and catfish that's made them a living.
"If they keep going like they are right now, they'll put commercial fishermen out of business here in the fresh water," says Briney.
Detected less than 50 miles from Chicago and Lake Michigan, underwater electrical barriers are tested to jolt the carp away from a canal leading to the Great Lakes and an ecological nightmare.
"If these guys establish themselves to the numbers that we're seeing in the Illinois River that could provide some catastrophic results," says Mark Pegg, of the Illinois natural history survey.
Once they were just a laughing matter, but now fishermen, like Gregorson, are cussing their luck.
"If rabbits was like them things, I'd be happier than hell," he says. "I like to shoot rabbits."
Suddenly, it's not quite so funny anymore.