Oder river: mystery of mass die-off of fish lingers as no toxic substances found

Polish scientists only found elevated salt levels after thousands of dead fish were found floating in the central European waterway

Mystery continues to surround the cause behind a catastrophic" mass die-off of fish in the Oder River, after Polish scientists said laboratory tests found elevated salt levels but no other toxic substances in the central European waterway.

German municipalities have banned bathing and fishing in the Oder after thousands of dead fish were found floating in the 520 mile (840km) river, which runs from the Czech Republic to the Baltic Sea along the border between Germany and Poland.