In 2002, a Maryland angler caught a fish unlike anything he had seen before. The discovery sparked panic, inspired horror movies and the snakehead species became one of America's most notorious invasive fish

A quiet fishing trip in Maryland turned into the start of one of America's strangest invasive species stories. When an angler caught an unfamiliar fish in a small pond in Crofton, he had no idea the discovery would lead to a wildlife investigation, public panic and even horror movies. The fish was a northern snakehead, a predator native to parts of Asia that had somehow made its way into Maryland waters.

The famous Crofton discovery happened in 2002, according to records from the US Fish and Wildlife Service and US Geological Survey. What made the case particularly worrying was that officials later found hundreds of young snakeheads in the same pond, showing that the fish had already reproduced.

Why the snakehead worried wildlife officials

The northern snakehead (Channa argus) has several traits that make it unusually tough. It can breathe air, survive in warm and oxygen-poor water and, under suitable conditions, live outside water for days. It is also a predator that eats fish, amphibians, reptiles and insects.


Its ability to survive in shallow water was one reason officials were concerned about its possible spread into rivers and other habitats.

“You’re not gonna find any other fish, if any self-respecting fish, in 95-degree water in the middle of August that’s a foot deep. But you’ll find snakeheads there.” — John Odenkirk, Virginia Department of Wildlife Resources, as quoted by the USFWS.

Officials treated the Crofton population as a serious threat and used rotenone to remove the fish. The USFWS says the operation found thousands of juvenile snakeheads, confirming that the population had successfully bred.

From invasive fish to horror movie material

The snakehead soon became a media sensation. Reports focused on its snake-like appearance, teeth, ability to breathe air and supposed ability to “walk” between waterways. The public reaction became much bigger than the scientific evidence, with terms such as “frankenfish” and “fishzilla” appearing in coverage.

The fascination also reached Hollywood. Three feature-length horror movies based around snakeheads were released between 2004 and 2006, turning an invasive species issue into a monster-movie storyline.

In reality, the fish was not the man-eating creature some reports made it out to be. The USFWS says snakeheads do not pose the direct threat to humans that early stories sometimes suggested.

The snakehead story is still complicated

The Crofton population was eradicated, but northern snakeheads eventually became established in other waterways, including the Potomac River. They are now found in several states.

Scientists have also found that their impact is not identical everywhere. In some areas, there are concerns about declining catches of native fish, while in other waterways native sportfish have continued to thrive alongside snakeheads.

“We don’t know what those impacts are going to be. They’re going to be different in every single watershed they show up in.” — Josh Newhard, Maryland Fish and Wildlife Conservation Office, as quoted by the USFWS.

The fish that once caused widespread fear has even become popular with some anglers because of its aggressive strikes and strong fight. For wildlife officials, though, the Crofton discovery remains an important warning: non-native fish should never be released into unfamiliar waters, because the consequences can take years to understand.