From 25th of February to 24th May I spent 3 months of work stay at the Umea University (Umea, Sweden). Under the supervision of Tomas Brodin from the Department of Ecology and Environmental Sciences I run the experiment focused on behavioural changes of fish caused by action of several selected pharmaceuticals which are commonly presented in open waters. Another aim of the experiment was to describe if and how much are these compounds able to bioaccumulate in living organisms (fish). I came back with a great piece of knowledge concerning an impact of extraneous substances in aquatic environment and its evaluation. I also found new friends and experts with similar thinking in my field of interest for future collaboration. I would like to extend my gratitude to Erasmus + programme for financial support during this stay.