A second mass fish kill within a month has occurred in southern Lake Macquarie.
The Hunter Community Environment Centre said a Mannering Park resident notified it of the incident on Tuesday.
A follow-up inspection by group members revealed hundreds of dead fish mostly mullet, some bream, bat fish and whiting and a juvenile White spotted eagle ray concentrated in southern Wyee Bay.
An Environment Protection Authority spokeswoman said officers were onsite late on Tuesday collecting water and fish samples as part an investigation. The Department of Fisheries is also assisting.
It comes after an at Mannering Park early last month which killed thousands of fish.
An EPA investigation concluded that the incident was likely a natural event.
Water sampling, toxicity testing and analysis showed there are no significant findings of pesticides, metals or toxicity.
The sampling results for total nitrogen and total phosphorus were above the guideline values, which may indicate that disruption of sediment occurred.
"These results, along with analysis of weather conditions at the time, indicate the most likely cause of the deaths was from a combination of factors," an EPA statement issued last week said.
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