Mass fish die-off in German-Polish river blamed on unknown toxic substance

Dead fish float on the surface of the Oder river, as water has been contaminated and is causing the mass extinction of fish in the river, in Bielinek, Poland, August, 11, 2022. Cezary Aszkiełowicz/Agencja Wyborcza.pl via REUTERS

BERLIN (Reuters) - An unknown, highly toxic substance in the Oder river, which runs through Poland and Germany, appears to be the cause of a mass die-off of fish, the German state of Brandenburg's environment ministry said.

An analysis of river water from Monday showed evidence of "synthetic chemical substances, very probably also with toxic effects for vertebrates," the ministry said on Thursday, adding that it remained unclear how the substance entered the water.