Catch this land-walking fish? Don't toss it back - do this instead

(NEXSTAR) - A new sighting of the so-called "Frankenfish" has prompted renewed warnings from wildlife officials that you shouldn’t just throw it back. 

While Frankenfish can conjure nightmarish images, it’s really a northern snakehead fish, or Channa argus. It may appear like a normal fish, but it has a special ability: it can breathe air, allowing it to slither onto land to find better water to swim in.

If they are able to stay moist, the snakehead can survive for up to four days out of the water, the California Department of Fish and Wildlife says. 

The freshwater fish is originally from East Asia and is considered invasive because it preys on and competes with native species, according to the U.S. Department of Agriculture’s National Invasive Species Information Center.

The first discovery of the Frankenfish was in California in 1997, according to the U.S. Geological Society. Since then, the species has been observed in 16 other states and the nation's capital: Arkansas, Connecticut, Delaware, Florida, Georgia, Illinois, Louisiana, Maryland, Maine, Mississippi, Missouri, New Jersey, New York, North Carolina, Pennsylvania, and Virginia, and the District of Columbia.

Last week, a northern snakehead was found in southeastern Missouri, marking the third reported sighting this year. A sighting was reported in Pennsylvania, and Louisiana recorded its first-ever snakehead discovery in early June.

How to spot one

The northern snakehead fish’s appearance lives up to its name. It’s long and thin with a dorsal fin that runs the length of its body, USGS explains. The fish’s brown skin and dark blotches almost make it look like a boa constrictor or another snake.

The sharp-toothed northern snakehead can grow to be three feet in length. 

The fish is akin to the Bowfin, according to officials, and the pair are often confused. Noticeable differences include their bottom fins: a Bowfin’s anal fin is short, while a northern snakehead’s is long, and a Bowfin’s pelvic fin appears in its belly region, while a northern snakehead’s is almost directly below its pectoral fin.

Federal officials say that though northern snakeheads prefer to live in shallow, stagnant ponds or swamps, and slow muddy streams, they have been spotted in canals, reservoirs, lakes and rivers. The first confirmed U.S. discovery of the fish, for example, was in southern California’s Silverwood Lake reservoir. 

What to do if you catch one

Because the Frankenfish is invasive, it’s best not to throw it back in the water. You also can’t toss it on shore to die (remember, it can breathe air and slither across land). 

Instead, federal authorities recommend killing the fish by putting it in a freezer or on ice for an extended period of time. If you’re able, you should also take a photograph of the fish for positive identification later and note the size of the fish, where you caught or saw it, and how many you caught or saw. 

Then, report the catch or sighting to your nearest fish and game agency, or the U.S. Fish and Wildlife Service at 703-358-2148. If you catch or see a northern snakehead in California, you are asked to contact the CDFW’s Invasive Species Program online, via email, or by calling 866-440-9530.