Abstract: The Morava River and the Thaya River forms the permeating axis of the Danube migrant fish species on the territory of the Czech Republic. Both rivers are a significant European migration routes. For this reason, these rivers are subject of intensive investment activities, conceptual studies and strategic migration plans. In both cases, these are border rivers, so there also takes place intensive cross-border international cooperation. There will be described the whole range of ongoing activities in our oral presentation. Then we will focused on detail of the project of ensuring migration of fish on the Thaya River in the National Park Podyjí, which is processed in a Czech-Austrian cooperation and on the project addressing migration permeability of the border stretch of the river Morava, which is solved by joint Czech-Slovak project. We believe that the international dimension of this issue represents a significant contribution of both projects.