JANESVILLE, Wis. - A carnivorous alien fish known for its voracious appetite and ability to wriggle short distances on land has been found in southern Wisconsin's Rock River. <br /><br />The discovery of the 2-foot-long giant snakehead by the state Department of Natural Resources marks the first time the species, a native of Asia, has been found in Wisconsin waters, where officials said it may not survive the winter cold. <br /><br />"This was a real wake-up call," said Mike Staggs, director of fisheries at the DNR. <br /><br />The giant snakehead can grow to more than three feet in length, and fish managers say that with no natural predator, it could change the local fish population and introduce new diseases. <br /><br />A year ago, wildlife officials in Maryland killed six adult and more than 1,000 juvenile northern snakehead, a close relative to the giant snakehead, found in a pond. <br /><br />The DNR found the giant snakehead during a routine fish survey of the Rock River Sept. 4.<br /><br /> The DNR said an employee misidentified the fish as a native bowfin. It was photographed and released before the DNR later concluded it was a snakehead. <br /><br />Two crews were sent back to the river last Thursday and three more crews went back Tuesday to look for evidence of snakeheads but found none, Staggs said. <br /><br />Staggs said the results indicate the fish does not appear to be widespread in the river, and the individual snakehead likely was released by a hobbyist after outgrowing an aquarium. <br /><br />Releasing aquarium fish into the wild in Wisconsin is illegal. <br /><br />It's unlikely the giant snakehead could survive the cold water of a Wisconsin winter, Staggs said. <br /><br /> 
