Why are so many fish dying in Rome's river Tiber?

Pesticides may be the reason for the death of Rome's fish.

Rome authorities continue to investigate the cause behind the mysterious death of hundreds of fish in the city's river Tiber on 30 May.

Initial tests have proved inconclusive and further testing is underway, however police do not believe the phenomenon relates to deliberate illegal dumping of toxic material into the river.

The capital's environment department is however working on the theory that the mass death of the fish relates to insecticides used in corn crops, abundant in farms north of Rome, reports online newspaper RomaToday.

The pesticide in question is believed to be a form of neonicotinoid which may have been washed into the Tevere by heavy rain at a time when the river's water levels were much lower than normal.

In April 2018 the European Union banned the use of three controversial neonicotinoid insecticides on all crops grown outdoors. The ban followed a respected scientific review which concluded that the insecticides posed a high risk to wild bees and honeybees.

As investigations continue in Rome, authorities are removing the fish carcasses to avoid health problems for those who frequent the banks of the Tevere.

Photo La Repubblica