This hits close to home, since I'm employed by the aquarium industry, and the snakeheads that are being found in US waters are certainly the result of hobbyists ridding themselves of a fish that has grown too large for their current aquarium set up. I was contacted about this issue when it hit the news in Maryland; did a phone interview for the Bassmaster newspaper that's published every couple of weeks.
Snakeheads are a tropcial family, hailing largely from Madagascar. In their home waters, they've ironically been hit pretty hard by the introduction of North American gamefish species such as largemouth bass. Anyone who has kept a snakehead in an aquarium for any length of time will tell you that it's a much more aggressive feeder than any of our native species, and that includes the pike family members, in my opinion. These fish are pike-like in body shape, with a mouth diameter roughly the same as the overall body diameter; they move very quickly in short bursts, having a semi-circular caudal fin shape which is more useful for maneuvering rather than sustained speed. I would think of them as a cross between a largemouth and a pike. These are tropical fish and as such the only way that they'll be able to survive the Winter is to be in an area where heated water enters the system, such as in the outflow of a power plant. Barring that or some similar scenario, those fish are dead as soon as the water temp drops much below 70. The fish grow very rapidly and given the majority of a warm season to exist in a body of water, one fish could do some pretty significant damage to the stock of forage fish and even smaller predatory species, as well as the young of those which grow to larger proportions.
The good news is that fish feed so aggressively and without regard, you could catch one easily with anything that remotely resembles a forage fish. In other words, I wouldn't rank them very high up on the scale of piscine intelligence, so they should be relatively simple to extract from a body of water. Additionally, these guys have the internal morphology of gars and bowfins, so they breathe air and typically hang out at the water's surface, making them easier to spot. Fish for them as you would for pike.
Aquarium hobbyists, I have found, are largely an irresponsible group of people when it comes to providing the proper care and thinking their decisions through regarding fish such as this one that can grow so quickly. Sale of snakeheads in the US should probably be banned, as such.