Giant snakehead are the antidote to a day behind static rods. They live in weed, in shallow margins and in flooded scrub, they are aggressive, and they take a surface lure with a hole in the water and no warning at all.
The best of it is sight fishing to fry balls. Adult snakehead guard a tight cloud of young, the cloud is visible from ten metres away as a shimmer on the surface, and a lure landed near it gets attacked by both parents rather than eaten out of hunger.
Tackle is ordinary bass gear and can be brought from home in a bag. A medium heavy baitcaster, braid, a short heavy leader because the teeth are real, and a handful of frogs, poppers and shallow divers.
The fish are not enormous by Thai standards, and it does not matter. A four kilo snakehead hitting a walking frog in a foot of water is more exciting than a forty kilo catfish taken on a float, and there is no comparison in effort. If you are building a trip around this rather than adding it to one, a full rundown of fishing in Thailand is worth reading before you book anything.
Reservoirs north and west of Bangkok hold them, as do irrigation klongs almost everywhere. Local knowledge is the whole game and a guide for one day will teach you more than a month of wandering.