Like other carp-producing countries in Europe, Serbian pond farming has a long history and a strong tradition. To understand the background of the production and the functioning of the farming technology, we can get an idea of how a pond farm works. These ponds are known locally as the Óbecse fish pond system, and are located close to the Serbian-Hungarian border. The fish ponds were established in 1968 and are located between the cadastral municipalities of Óbecse and Bácsföldvár. The fish ponds cover an area of 650 ha and are supplied with water by the Ferenc- canal with gravity water control. The used water is discharged into the "Old Tisza" after the end of the production technology. The average annual production of the pond system over the last 20 years is 450 - 500 tonnes of market size carp, 150 tonnes of market size silver carp , 50 tonnes of grasscarp , 3 - 3 tonnes of European catfish and pike perch, 120 - 150 tonnes of two-summer old carp juvenile and 30 - 50 tonnes of one-summer old carp fingerling.
In Serbia, two types of production technology are used: two-year and three-year production systems (Table 1).
The two-year production system is used for intensive pond fish farming systems, using only extruded feed concentrates. The three-year production system is a traditional cereal-based feeding system, where concentrates are used only in the first year of rearing, and only cereals are fed to the stock in the second and third years.
In small and intensive ponds, aerators are used to enrich the water with oxygen, both deep and surface aerators. In case the amount of feed exceeds 40 - 120 kg/ha, aerators should be operated during the night (mostly between 18 - 06 h).
European carp producers are divided on the future of feeding: the use of cereal-based feeds and complete feeds will be determined primarily by economic factors.
A good example of the use of complete feeds is what our Serbian fish farmers in Vojvodina territory are using in their pond farming systems. Due to the strong pressure from cormorant, they have been forced to rapidly increase the population of one-summer - and two-summer old carp, which they feed with complete feeds.
The results show that the grain-based feeding (2.5 - 7.0 kg FCR) resulted in an average of 5.0 kg, which is similar to the Hungarian results (based on literature data, 4.0 kg of grain can produce 1.0 kg of fish meat).
The results obtained with complete feeding are thought-provoking. The FCR of 1.78 kg of feed to produce 1.0 kg of fish meat is an excellent result, which supports the argument that there is a justification for feeding complete diets for certain carp age classes.
Serbian pond farmers are also struggling with water quality problems, which can only be alleviated by continuous monitoring and control. The KHV is also present in Serbia. Its management and prevention is a priority task and issue of everyday production organisation.
It is interesting to consider how the 2-year carp production system, the current input material prices and the drastic changes in the weather condition could be introduced into the production technology of other European countries.