Photo: East News Emergency workers remove dead fish from the Oder river near the village of Krajnik Dolny on August 15, 2022 in north-western Poland on the German border. In recent days thousands of dead fish have been found in various parts of the second largest Polish river - Oder. Polish authorities are trying to establish the source of the possible toxic pollution, which kills not only fish but other water animals i.e. beavers. On a stretch of almost 200 kilometres, Oder is a natural border between Poland and Germany.