Heather Chen wrote this article in BBC:

Millions of dead fish have washed up in a river near a small Australian town, in a phenomenon state officials say is related to the “heatwave conditions” that are sweeping the country.

Video emerged this week showing masses of dead fish floating at the Menindee Weir pool near Broken Hill, CNN affiliate 9News Australia reported.

“Significant volumes” of fish, including carp and bony herring, along with nutrients and organic matter from the flood plain, have been forced back up the river due to the hot weather, according to the Department of Primary Industries (DPI) in New South Wales.

“These fish deaths are related to low oxygen levels in the water (hypoxia) as flood waters recede,” it explained in a statement this week.

“This event is ongoing as a heatwave… continues to put further stress on a system that has experienced extreme conditions from wide-scale flooding,” the DPI said.

“The current hot weather in the region is also exacerbating hypoxia, as warmer water holds less oxygen than cold water and fish have higher oxygen needs at warmer temperatures,” it added.

Heatwaves across Australia have become more frequent and intense as climate change worsens and global temperatures continue to rise.

Experts and government agencies have warned that Australia will continue to see spikes in extreme rainfall and heat, as well as more dangerous fires.

Menindee, a rural town in the far west of New South Wales state, has a population of around 500 residents, according to census figures.

Dead fish sightings were also reported this week in the Macquarie Valley, where there are both suburbs and a national park.

This wasn’t the first time Menindee residents have witnessed mass fish deaths.

Thousands of dead fish were reported in the area in February and a similar event occurred in the region in 2019.