The thesis consists of theoretical and empirical part. The aim of the theoretical part of the thesis is to define the influence of small hydropower plants on ichtyofauna of watercourse. The paper briefly describes different types of small hydropower plants and deals with ecological and environmental aspects and problems they can cause. It describes negative impacts of small hydropower plants on the living conditions of ichtyofauna. In the empirical part we propose suitable nature friendly measures which lead to improving the living conditions of ichthyofauna as influenced by the existence of small hydropower plants. We also propose necessary natural adjustments such as fish ladders and fish shelters. Another measure we have proposed is to alter and plant riverbank vegetation.