Potrava násady kapra (Cyprinus carpio L.) v rybnících - analýza obsahu zažívadel.

The aim of this bachelor thesis was to comprehensively evaluate the diet of two-year old common carp in semi-intensive pond culture from the stage of two-year carp (K2) to the stage of market carp (Kt). The extent to which the carp use natural and presented food and whether its composition changes during the season was monitored. The experiment itself was part of a large-scale GAČR project (Nutrients from Fish or Nutrition for Fish: Revealing Hidden Risk of Pollution and Nutrient Retention in Ponds through Nutritional Bioenergetics of Fish), which was conducted at the experimental facility of the VÚRH Vodňany. The experiment of food study was conducted in three ponds (0.16 ha), which were slowly filled from mid-April onwards, for the development of natural food after being left dry. Subsequently, 150 individuals of carp (337 ? 57 g) and 35 individuals of pikeperch (S. lucioperca L.; W=14.5 ? 38.8 g), were stocked on 26th April 2022 to prevent the development of undesirable fish species. Carp rearing lasted 162 days, during which time carp diet was monitored approximately once a month using the flushing method of Faina (1975). The contents of intestines of four carps were collected from each pond, at each date. At the beginning of the season, the diversity of the diet was high. Zooplankton was the most abundant food component throughout the entire experiment. However, if we consider the size of the feeding organisms, zoobenthos, consisting mainly of chironomid larvae, played a significant role in the diet of the carp at the beginning of the season. As the season progressed, the number of zoobenthos individuals decreased, while the number of zooplanktonic organisms in the diet increased, mostly represented by planktonic cladocerans and copepods. These two groups of organisms also had the highest frequency of occurrence and abundance in the digestive tract throughout the experiment. Along the season, in addition to the increasing abundance of zooplanktonic organisms, the proportion of grains in the carp diet also increased