Have you ever caught a snakehead fish?

You’d better hope not.

Distinctive fish native to Asia, snakeheads are an invasive species, and a particularly nasty one. Very aggressive and loaded with teeth, capable of traveling out of water, they "have the potential to reduce or even eliminate native fish populations and alter aquatic communities," according to the New York State Department of Environmental Conservation web site.

Snakeheads, now quite common in some parts of coastal Maryland, are believed to have entered New York waters as a result of aquarium dumping. They are regarded as "injurious wildlife" by the federal government, which restricts their sale and movement, and New York state prohibits their sale, transport and possession.

Snakeheads have been found on Long Island and in Orange County. Believe me, you don’t want to see them in any waters in Central New York, but they are just one of the scores of invasive and often detrimental plant, animal and bird species that have invaded North America.

Ever have your foot sliced up a bit by Zebra mussels while swimming in your favorite lake? Or have you caught dozens of round gobies as you tried to zero in on the bass on Lake Ontario? Those invasive species have made obvious and significant impact on our environment and recreational opportunities.

Japanese knotweed is another easily identifiable invasive species that is a big pain. I remember when it first started showing up along the banks of local creeks, sometimes making fishing a bit more difficult. It resembles bamboo, and it grows incredibly quickly in thick clusters dozens of yards across, frequently crowding out native vegetation. It is very difficult to discourage.

There are a great many pestilent critters and plants out there, some purposefully introduced — starlings and carp, for example, going back well over a century — and others arriving by hitching rides on and in ships, trucks and trains, with still others being released from or escaping from captivity. They include Eurasian boars, Emerald ash borers, Spotted lantern flies, hydrilla, water chestnut and much else.

Invasive species tend to flourish when they first arrive, then seem to eat themselves out of house and home and reduce their populations. But they never stop being a problem for habitat, native fish, wildlife and trees, and crops and livestock.

A particularly interesting one is Didymo, which also is known as "rock snot."

A decade ago it was the driving force behind some states banning and others discouraging the use of felt-soled waders and wading boots. It was believed that Didymo, a type of algae, was spread in part by clinging to felt and that other substances were less likely to carry and spread it, so rubber-soled waders and boots became the order of the day. A lot of anglers resented that, because they believed felt is by far the best thing we have to grip river bottoms and provide stability for waders. And they didn’t want to have to buy new gear.

The fact that Didymo can cling to clothing, boats, hooks, lines, lures and about anything else that touches the water made the fight against it even more discouraging.

But then the question arose as to whether "rock snot" had always been with us. Apparently, yes. It is now believed to be native to the Northern Hemisphere around the globe. It is messy looking stuff, and it can change the invertebrate makeup of a stream, something most anglers probably wouldn’t like. Some scientists feel it is more common than in the past because of climate change.

One thing is for sure: Getting rid of invasive species — fish or fowl, animal or vegetable, insects, whatever — is almost impossible once they get here. If you can think of any that have been eradicated, please let me know.

So what do we do? Preventing invasives from getting a foothold in the first place is the number one remedy, but that isn’t so easy. For example, the advice on how to make sure your boots don’t carry rock snot to another piece of water include cleaning them thoroughly with very hot water and then drying them completely before the next use; immersing them in bleach for however long you think appropriate, or freezing all your gear for who knows how long. I can assure you very few anglers actually do any of those things.

However, the DEC does have some good advice, such as that provided at www.dec.ny.gov/animals/6986.html. You’ll also find links there to the DEC’s invasive species web page — https://www.dec.ny.gov/animals/265.html — and to the New York State Invasive Species Clearinghouse — http://nyis.info/.

Write to John Pitarresi at 60 Pearl Street, New Hartford, N.Y. 13413 or jcpitarresi41@gmail.com or call him at 315-724-5266.