Scientists began poisoning a Maryland pond this week, hoping to kill Chinese northern snakehead fish discovered there this summer. This is the beginning of the end for the snakehead fish, said Heather Lynch, a spokeswoman for Marylands Department of Natural Resources. Time is up. Snakeheads are voracious predators that can grow to 3 feet, and can slither over land in search of new prey-stocked bodies of water. Their presence in the pond alarmed wildlife biologists, who feared the alien species could escape and take over Marylands waterways. Snakeheads are normally found in China, but a local man dumped a pair into the pond two years ago after they ate all his goldfish and outgrew his aquarium.