Most are clubbed to death in festive street markets and served up on Christmas Eve. The lucky ones _ in homes where children grow attached to the fish in the bathtub _ are released back into the rivers.
More than 200 tons of carp will be captured in four days starting Monday from a huge pond in southern Bohemia as fishermen wade into the frigid waters, using a centuries-old technique of slowly scooping them up from the pond's muddy surface with nets supported by long wooden poles before placing them in water containers.
It's the moment Czechs know the countdown to Christmas has begun.
The lowly carp may be derided in some parts of the world, but here it's a must-have Christmas delicacy. Czechs gather for fish soup or fry them in breadcrumbs. They're even said to bring good fortune if you keep some of their scales in your wallet.
Some keep the fish alive in the bathtub after buying them at market just before Christmas. Some, though, stand back as the vendor kills them there and then with a club.
The carp _ glowing brown, green and golden in the dawn light _ wriggled furiously as they were snared and brought slowly to land on Monday.
"There's no reason," to change the technique, said Stanislav Vago, the caretaker of the 200-hectare (494-acre) Bosilecky pond, which is one of the oldest in the country and dates to 1355. "It's impossible, anyway. You can't find a better way."
Around him stood dozens of fishermen with green waterproofs sorting the fish.
It's a scene played out across Czech Republic in November, but particularly in southern Bohemia near the border with Austria.
The region has an elaborate network of about 500 carp ponds interconnected with manmade canals that started to be dug in the mid-14th century. There were about 25,000 of them by the turn of the 16th century in the entire country.
Experts say the network has helped spare the area significant damage from flooding, especially during devastating floods that wreaked havoc in Prague and much of the country in 2002.
To some, such fuss over eating carp might seem odd.
In Australia, where carp has been introduced illegally, there's a saying that "a good carp is the dead carp" as it poses a threat to native fish species. In the United States, carp, which is imported from Asia, is considered a risk for the ecosystem of the Great Lakes due to their size and rapid reproduction.
Ales Kriz, a manager of Fisheries Trebon AS, the leading Czech fresh water producer, says attitudes may be changing and that Czech, cereal-raised carp are being exported to Austria, Germany, Italy, Poland, Hungary, Slovakia and even France. In fact, some 60 percent of fish produced by his company is now sold abroad.
Czechs, for the most part big meat-lovers, only tend to eat carp at Christmas. And fish in general isn't so popular regardless of the season, with an average person here consuming just 1.37 kilograms (3.02 pounds) of fish a year.