A drop in temperatures and some rain is likely behind another mass fish kill reported along the Darling River in far western NSW, the state government says.
Local Graeme McCrabb on Monday morning posted photos on social media of floating dead fish in the weir pool at Menindee.
The NSW Department of Primary Industries has sent officers to investigate the event, which it believes has affected "large numbers of bony bream and smaller numbers of other species".
"It is likely linked to some rain and cooler temperatures in the Menindee area following an extended period of very hot weather," a spokeswoman said in a statement to AAP.
Central Darling Shire Council has hired a clean-up operator which will also record information about the event, the department said.
Menindee resident Rob Gregory said there were at least 200-to-300 dead bony bream, as well as some native species.
"There are lots of yabbies crawling up the bank ... they must be suffocating," he told AAP.
"It's a shame."
Mr Gregory said the latest fish to die would have likely been survivors from previous events.
Up to a million fish died along the Darling River at Menindee earlier in January, while thousands were also found dead almost 900km away along the Macintyre River.
Central Darling Shire general manager Greg Hill, who is in charge of the clean-up, fears the latest mass kill could be as large.
"It's fairly big," Mr Hill told AAP.
