World Aquaculture 21 ponds during the first year of carp life, 2) grow-out ponds for two- to four-year-old fish (two- to three-year-old fish, at present), and 3) marketing ponds for marketable fish production until the 5th-6th year (maximum four-year-old fish at present). The overall carp farming technology was well developed and Czech carps were highly appreciated in domestic and foreign markets. In the beginning of the 17th century, the era of progressive development of pond culture ended. At the same time, all of Europe was affected by the Thirty Years’ War (16181648). Because of enormous human loss of life, the economy was disrupted and pond farming ceased. This period of the fall of pond culture lasted until the end of 19th century, when carp pond farming was revived. Under central European conditions, carp has been recognized as the most suitable pond fish for controlled farming. Its main advantages for this kind of culture are, above all, high fecundity, good growth rate, high resistance to unfavorable environmental and climatic conditions, good ability to use available natural food as well as low-protein feeds, good meat quality, along with high disease resistance and capability to withstand handling and transportation. No wonder carp is by far the most important fish of Czech pond aquaculture (Figure 4). Current State-of-the-Art in the Czech Republic Generally aquaculture production in the Czech Republic is characterized by extensive and semi-intensive fish farming in ponds. Production averages around 450 – 500 kg per ha, with individual farms ranging between 200 and 800 (up to 1000) kg per ha. Currently, yearly fish production fluctuates between 17 to 21 thousand t for the last 20 years. Common carp is the dominant fish produced (86-88 percent), but polyculture is an important aspect of pond farming in the Czech Republic. Chinese carps (grass carp, Ctenopharyngodon idella; bighead carp, Aristichthys nobilis; and silver carp, Hypophthalmichthys molitrix) together with traditional supplementary fish (tench, Tinca tinca) and predatory species, such as pike, (Esox lucius), zander (Sander lucioperca), European catfish (Silurus glanis), and perch (Perca spp.) are all produced in ponds. About 25 to 30 percent of carp production depends on supplementary feeding; however, an overwhelming majority of carp production is based on natural food – zooplankton and zoobenthos. Wheat and barley are the basic feeds used in ponds. Recently feeding and fertilization have been severely restricted by law because of eutrophication (algal blooms) in receiving waters caused by high nutrient loading. Now, only organic manure is applied in very small amounts and lime is mainly used to counter negative effects. Leading Role of Common Carp Production in Central Europe Live fish, carp in particular, is the most important product of Czech aquaculture because carp is a traditional Czech dish. In recent years, the domestic consumption of carp has increased moderately but steadily. This increase may be related to the ecological approach to farming. A high proporFig. 3. The pond system in Vodňany region on the map by Johannes Christoph Müller from 1720. Fig. 4. A monument to common carp in Třeboň, Southern Bohemia in the heart of the largest area of fish ponds in the Czech Republic. (Photo by Zdeněk Adámek.) Fig. 5. Pond harvesting, a typical autumn scene on the Svět pond (215 ha) near Třeboň. (Photo by Zdeněk Adámek.)
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