Thousands Of Dead Fish Have Washed Up In Sydney As Experts Warn Of Another Mass Death Event


In some truly apocalyptic news, thousands of fish have died around Sydney’s waterways due to heavy rains and experts fear we could be on the brink of a fish kill catastrophe.

A surge of de-oxygenated “black water” in the Parramatta River at Rydalmere has killed at least 4000 native fish and threatens to kill a million more in Menindee Lakes, which could infect the Darling River in in the state’s far west. 

The black water event at Rydalmere on Monday was just one mass fish death in and around Sydney in recent weeks.

A separate fish kill event occurred at Haslams Creek on Feb 3, as well as reports of dead fish washing up at Wentworth Point and Rhodes. 

The EPA conducted water quality analysis at both sites and identified low dissolved oxygen caused by rain resulted in the fish kills.

Low oxygen or black water occurs when loads of debris like mud, sticks and leaves are washed off the land by floodwaters. When organic material breaks down the process sucks oxygen out of the water, leaving the fish to suffocate. It is also exacerbated by high temperatures.

“It is distressing to see a significant number of fish killed and a variety of species impacted,” an EPA spokesperson said in a statement.

Experts are now concerned for more deaths as heavy rain continues.

The NSW Environment Department’s water planning director Allan Raine told the Sydney Morning Herald the floodwaters and debris could flow down the Darling River into the Menindee Lakes systems, and possibly further into the Lower Darling River.

“The scale of this hypoxic black water event is substantial and there is a very high risk of fish deaths unless cooler temperatures continue,” Raine said.

“The two major risks over the coming weeks are the floodwaters that are low in dissolved oxygen levels moving into the Menindee Lakes and the potential for floodwaters on the lower Darling floodplain to flow into the lower Darling River.”

Some pretty harrowing footage has emerged online of people discovering dead fish and prawns all over river banks, including one fisherman who filmed the scenes on Monday.

If predictions come to pass this event could be worse than the fish kill in 2019 that claimed a million native fish.

Environmentalists and farmers at the time blamed the Murray Darling Basin Authority’s poor management of the Menindee Lakes for the build up of blue-green algae that was responsible for the catastrophe. The toxic algae developed in stagnant pools after drought, and then rains washed it into the water system and poisoned the fish

The EPA continues to monitor the water quality in the area and is working with Parramatta Council to clean-up the dead fish in the city’s west. For now, let’s hope this is the end of it.