Four states now have the eels, which can gobble up all kinds of aquatic life.
No one has figured out how to kill off the creatures.
The eels are highly adaptable. They can change sex. They can burrow in mud and survive for weeks without food. They can also crawl over land to other bodies of water.
Officials believe someone may have had the eels as exotic pets and dumped them in the waterway.
Information from: The Star-Ledger, http://www.nj.com/starledger