Here's Wikipedia's take on how to catch them:
"Silver carp are filter feeders, and thus are difficult to catch on typical hook and line gear. Special methods have been developed for these fish, the most important being the "suspension method", usually consisting of a large dough ball that disintegrates slowly, surrounded by a nest of tiny hooks that are embedded in the bait.The entire apparatus is suspended below a large bobber. The fish feed on the small particles that are released from the dough ball and will bump against the dough ball, with the intention of breaking off more small particles that can be filtered from the water, eventually becoming hooked on the tiny hooks.
In some areas, it is also legal to use "snagging gear" in which large, weighted treble hooks are jerked through the water, to snag the fish.
In the United States, silver carp are also popular targets for bowfishermen; they are shot both in the water and in the air. In the latter case, boats are used to scare the fish and entice them to jump, and the fish are shot when they jump."
Thai fishermen at BoSang can't use the above referenced "Suspension Method"because the Striped Catfish which they are not permitted to remove for food at the park would grab the whole ball of bait and become hopelessly entangled in the tiny hooks.
Take a look at this incredible BBC video of these same fish on the Illinois River in the USA where they are considered a serious eco-threat to native species:
It's worth noting that these fish can grow to close to 100lbs!
I know there are numerous other videos of this phenomenon on YouTube but no-one does Nature like the BBC!