FILE PHOTO: Dead fish are removed from the Oder river, as water contamination is believed to be the cause of a mass fish die-off, by the German border, in Krajnik Dolny, Poland, August 13, 2022. REUTERS/Annegret Hilse/File Photo
WARSAW (Reuters) - Poison cannot be ruled out as the cause of a mass die-off of fish in the Oder river but tests so far have not proven toxic substances were to blame, Polish Environment Minister Anna Moskwa said on Sunday.
Tonnes of dead fish have been found since late July in the river Oder, which runs through Germany and Poland. Both countries have said they believe a toxic substance is to blame, but have yet to identify what it is.
