by Whit Gibbons

April 2, 2017

Q: I saw a recent article about invasions of tropical fish that are causing environmental problems in canals in southern Florida. I have also heard that a foreign fish called a “snakehead,” which has big teeth and can travel over land, has been introduced into rivers in Alabama and other southern states. If these reports are true, shouldn’t we be concerned?

A: Southern Florida is full of exotic animals and plants that have become naturalized. Many small tropical fish have been released from home aquariums by people who were moving from the area or simply got tired of having an aquarium. Because of the warm climate and the absence of their natural predators, many fishes from South America, Asia or Africa with similar climates to Florida have survived and produced offspring. As with many nonnative animals and plants that are introduced into a region, some successfully compete with native species and can even replace them under certain conditions.

As for the group of fishes known as snakeheads, their ecological impacts are still uncertain. According to the U.S. Geological Survey, the northern snakehead is native to Russia, China and Korea. In the United States, one was first reported in the wild in California, but they have not become established on the West Coast.

However, this invasive species is now present in parts of Virginia and the Chesapeake Bay area and a pond in New York, as well as in some river drainages in Arkansas. Its occurrence in Alabama and other southern states has not been documented. If you catch one, report it to your state wildlife department.

The open mouth of a snakehead can lead someone to think first that dental work might be appropriate and second that being bitten would be a memorable but highly negative experience.

According to Pam Fuller, a USGS scientist who conducts research on snakeheads and other nonnative fish species, they do have some nasty-looking teeth. But she adds, “it’s just a fish” and does not have an unusually impressive bite. Nonetheless, sticking your finger into the mouth of any big fish with sharp teeth is not advised.

In general appearance, northern snakeheads look like bowfins (aka cypress bass or mudfish), which occur naturally throughout much of the eastern United States. However, northern snakeheads have a long anal fin (the one on the belly in front of the tail) and a flattened head compared to the small anal fin and bullet-shape head of a bowfin.

In addition, bowfins have a black spot on the tail. Northern snakeheads reach body lengths of more than 2 feet. A related Asian species, the giant or bullseye snakehead, is now found in southern Florida and can be almost 4 feet long. The snakeheads found in Florida also have a spot on the tail like a bowfin.

Young snakeheads eat a variety of zooplankton and small aquatic insects. Adults eat other fish, sometimes one-third the length of their own bodies, as well as crawfish and frogs. Snakeheads are different from most other fish, which cannot survive for long out of water.

Adult northern snakeheads have gills but can also gulp air and have been documented to live out of water for up to four days. However, although a young one may travel overland for several feet, a full-grown adult is too large to move effectively, so your pet chihuahua will probably be safe if it can make it to the pet door.

Will snakeheads cause serious environmental problems where they become established? The most likely impact will be because snakeheads not only eat other fish but are also successful competitors with native fish that have the same food base.

Attempts to control invasive species like snakeheads, pythons and fire ants are often futile, and once established most such species are probably here to stay. If you are an angler, the best approach with the northern snakehead might be to find out what kind of bait they prefer.

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