They are illegal in a lot of states. What in the world would you want one for? There are plenty of legal fish that are large and interesting. They are a horribly invasive predator with the potential to decimate native ecosystems.
I recall hearing on some fishing shows I used to watch, and through personal research that those fish are extremely dangerous to the environment as they choke out a lot of other fish population. Some states have pronounced them illegal and they must be called into authority if found in the wild.
I'm not going to comment on whether or not it would be a good choice for an aquarium as it looks like others have already done this, but I do know that in order to bring them into the US the importer needs a permit. You also need a permit for each state line you cross with the fish for any reason (you or the importer). They are currently illegal to own or transport through the following states: Alabama, California, Florida, Texas, Virginia, and Washington as well as most major cities (Boston, Chicago, New York, St. Louis) and some municipalities. There could also be more recent laws I'm not familiar with.
The other major concern is aquarium size, if you are looking to keep one it would depend on the species. Example: a dwarf snakehead (5") could be kept in a 55 gallon if it was all by itself, but something like a northern snakehead woul require AT LEAST 500 gallons (and if it is one of the larger species you would also want reinforced glass instead of a standard aquarium as they can thrash and shatter normal glass.
EDIT: I should add that all permits have to go through the Federal Government (US Fish and Wildlife). As far as I am aware these are hard to get and you usually have to wait a long time and prove that you are expirienced with the wildlife you want to keep.
Last I heard, all Channa species were federally banned in 2002 as injurious species. They cannot be imported or transported anywhere in the US without a permit, which you cannot get as an aquariist. Therefore not legal in any state of the union. They are a particular problem in certain states due to having already been released in those areas.
Of course, if you don't live in the US, I suppose you have to check with your own governments. I believe some of the tropical species are still legal in Canada.
Pike cichlids are still available and very much like the channa without personal fear !
I had a snake head before all the hoopla ..EATING MACHINE !!!!
Seriously like 10 goldfish a day easy ...
A pike could be maintained much easier and there are several color variations .. No permit required !
I got one from a mall petshop as a teen. I couldn't afford to feed it.
goldfish > tried breeding guppies and swords > minnows from the bait store.
It was a pretty red fish. It was a predator. Teen boy approved! Take my allowance!
There was no internet to explain what a bad fish choice that was. I had it in a 15 gal or was it the 10?
Thank god I could only afford 1.