Predator Fish That Can Walk and Breathe Air Is Making Headway in the US

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Landwalking 'Snakehead' Fish Appears In Philadelphia
Northern snakehead fish swim in a tank at the Academy of Natural Sciences in Philadelphia, Pennsylvania. William Thomas Cain / Getty Images

It doesn't get much spookier than the toothy northern snakehead, a carnivorous fish that grows to at least three feet in length, can breathe air and can survive for several days out of water. It can survive for even longer periods in mud and moist environments. Oh, and it travels over land by wriggling its body along the ground.

The fish inspired exclamatory headlines when it made an appearance in New York City’s Central Park, but the more concerning news is that it keeps on showing up in places it shouldn't be. Snakeheads have been found in at last 14 states.

Most recently, it has been seen in a pond in Gwinnett County, Georgia — where wildlife officials recommend that snakeheads be killed immediately — and in the Monongahela River in Pittsburgh.

The fish that's making wildlife agencies skittish is an invasive species native to China, Malaysia, and Indonesia. Snakeheads are top predators and feed ravenously on other fish as well as frogs, crayfish, and aquatic insects. (Your puppies and children are safe.)

To make things worse, it's a fish with no natural predators in the U.S., it can spawn multiple times every year, and females release tens of thousands of eggs with each batch.

So, basically, they're huge, walking carnivorous fish that can live outside of water, have no predators, and possess a remarkable reproductive rate. Incredibly cool in an evolutionary sense, but at the same time: Houston, we have a problem.

After reports first surfaced of one of the fish being spotted in 2013 in Harlem Meer, a lake in the northeast corner of Central Park, environmental officials conducted surveys of the water. That particular batch of snakeheads is no longer thought to be alive, but there are others in the area seen much more recently.

Snakehead Fish Found In Lake Michigan
In this undated handout photo from the U.S. Department of Agriculture, a northern snakehead fish is held.

Getty Images

Where Did They Come From?

Snakeheads are sold in the U.S. both as food in Asian markets and as pets, according to a factsheet from U.S. Fish & Wildlife, and reproducing populations of snakeheads have been discovered in Maryland, California and Florida in addition to New York. Individual fish have also been caught in Maine, Massachusetts, Rhode Island, Hawaii, Maryland, Virginia, Pennsylvania, Georgia and Wisconsin.

The escapees are thought to have been purchased as pets, then set loose by owners who no longer wish to keep them. (However, in one remarkable story a Maryland man ordered a pair of live snakeheads from a market in New York's Chinatown to prepare a traditional soup to cure his ill sister. By the time the fish arrived, his sister had recovered, and he released them into a local pond. Oops.)

In 2012, the Maryland Department of Natural Resources Inland Fisheries set a $200 bounty for the successful capture and killing of any northern snakehead. (Perhaps the rest of the states mentioned here should consider a similar reward if they haven't already.)

Since then, scientists have been studying the snakehead's patterns. Wake Forest researchers discovered that the creatures will flee water that is too acidic, salty or high in carbon dioxide — and by flee, we mean they'll move across dry land to another body of water — which is exactly what we don't want them to do. The hope is that their work, published in the journal Integrative Organismal Biology, may give us clues on how to contain them.