Distraught locals at Menindee are again flooding social media with images and videos of dead and dying fish after another major die-off in the Darling River.

Videos and pictures posted to Facebook show struggling fish gasping for breath at the surface of the water as the carcasses of hundreds of smaller dead fish float around them near the town about 100km east of Broken Hill.

“Wake up this morning to this millions on (sic) fish dead again share this so sad Australia,” wrote Phillip Bottrell at about 8am today. His post quickly attracted more than 100 shares.

Another Menindee local posted photos and videos of a dying carp gasping at the surface as it died along with the floating carcasses of fish it had already outlasted.

Mr Gregory told AAP he saw at least 200-300 dead bony bream.

“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.

Other locals are again voicing their despair on social media, claiming mismanagement of the river system favouring large business interests upstream had killed the Darling and the Menindee Lakes.

South Australian Greens Senator Sarah Hanson-Young this morning took to Twitter to demand a Royal Commission.

“Our river system is in crisis and the environment is in collapse. Meanwhile the Water Minister is trying to bury critical reports, cover up mismanagement & blame drought. No, it’s greed - Cotton, corruption & climate change,” she wrote.

Federal Opposition leader Bill Shorten said the river faced an “ecological disaster”.

NSW Water Minister Blair Niall is due to make a statement on the latest disaster to strike the Darling, Australia’s second longest river after the Murray, this afternoon.

A spokeswoman for the NSW Department of Primary Industries said fisheries officers had been deployed to investigate the deaths in the Menindee weir pool.

“Reports from the area indicate the event has affected large numbers of bony bream and smaller numbers of other species,” the statement read.

“It is likely linked to some rain and cooler temperatures in the Menindee area following an extended period of very hot weather.

“Central Darling Shire Council has deployed a clean up operator who is also tasked with recording information about the event.”

The latest die off comes just weeks after about a million fish died in the Darling at Menindee, setting off an interstate blame game as NSW authorities blamed a blue-green algal bloom and hot weather.

Others blamed state and federal mismanagement of the river, which has stopped flowing in recent months and is completely dry in several areas.