KOŠTIALOVÁ, Iveta: Pollution of water sources and its consequences on fish [Bachelor Thesis] - Technical University in Zvolen, Fakulty of Forestry, Department of Intergrated Forest and Landscape Protection. Bachelor Thesis Supervisor: Ing. Pavol Hlaváč, PhD. Degree of professional qualification: bachelor, in short „Bc“. Zvolen: Zvolen: LF TU 2019, 50 p. This bachelor coursework is based on the topic of pollution of water sources and its consequences on fish life. There are not too many accidents on water flows in Slovakia, which lead to mass-scale deaths of water organisms. We focused more deeply on the area of upper and middle Hron. There are various reasons for perishing of the aquatic life. One of the main problems is that in most of the cases, the offender is unknown. For this reason, the people that cover this area and the specific water flow will not receive the compensation for the caused and later evaluated damage. However, the main cause of mass-scale fish kill is the weather, specifically high amount of rainfall or excessive temperatures.