Třeboň, town, southern Czech Republic, on the main road to Vienna. It lies in the basin of the Lužnice River, which is floored with heavy impermeable clays upon which a good deal of peat has formed. The area has many artificial lakes, and, since the Middle Ages, a freshwater fishing economy has been developed, chiefly with carp. The largest fishpond, laid out (1584–90) by Jakub Krčín, was named after the Rožmberk family, who founded Třeboň’s Augustinian monastery and promoted fish breeding. The town and its environs passed to the Schwarzenbergs, a powerful Austrian noble family, in 1660. A remarkable work of medieval pond husbandry is the Zlatá stoka (Golden Canal), which supplies the system with water from the Lužnice. The Svět fishpond (540 acres [220 hectares]) is used for training in water sports.
Wide stretches of water, rimmed with forest and successions of small fish pens, surround the old town, which is noted for its Gothic Church of St. Giles (1367) and Schwarzenberg Castle, which contains valuable archives. Třeboň also has a spa and a small textile industry. Pop. (2004 est.) 8,862.