The purpose of this diploma thesis which was carried out within the scope of the project LIFE „ YBBS-DANUBE CONFLUENCE “ was to investigate the migration behaviours of Chondrostoma nasus, Hucho hucho and Silurus glanis with the help of Radio telemetric controlling. In order to monitor migration patterns, 50 Nase, 3 Danube-salmon and 3 European Catfish were fitted with tracking devices and were tagged. The investigation period extended from November 2007 till the beginning of October 2008. The specific migrations of the tagged individuals are described and illustrated in this study. In addition, a detailed investigation of the migratory movements of the tagged fish during specific assigned seasons, was also conducted. The investigations of the migration movements show significant differences in the Home range, the complete migration and the depth habitation in the respective seasons. The seasons have been classified mainly into winter, pre-spawning, post-spawning and summer. Even though most of the tagged fish were spotted along the free flow course of the river, a few sightings were also made in the rooted backwater area and in the central reservoir. The recently erected fish ladder and the lift lock at the Danube power plant at Melk were not along the migration route of the tagged fish. The tagged fish used the dockyard for sporting boats at Luberegg as a retreat during winter. Thirty-two percent of the nase and two thirds of the Danube salmon observed during the study migrated to Pielach during the spawning season in order to spawn. Newly placed gravel embankments and islands during the course of the LIFE project ‘Wachau were used as a summer habitat by the nase. One of the observed Danube salmon migrated 13.5 km upstream the Pielach river, passing through 5 weirs/rock ramps, all of which were made passable as a part of the LIFE project ‘Lebensraum Huchen.