In a video that went viral on Wednesday, grazier Rob McBride and resident Dick Arnold lifted dead Murray cod fish out of the Darling River near Mr McBride's Tolarno Station.

"Look at these iconic fish of Australia being treated like this ... you'd have to be bloody disgusted with yourself," Mr Arnold said of the critically-endangered species.

The video was viewed nearly 3 million times in 24 hours and shared by close to 100,000 users.

Mr Blair said he understood public concern about the deaths - "one of the largest fish kills ever seen" and a "devastating ecological event" - but warned against the "political scaremongering" being directed at the government.

"We haven’t had the replenishment from any water coming in from the top of the system," he said, with the drought robbing the river system of almost all of the 4000 gigalitres it would have ordinarily received in the past six months.

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Mr Littleproud acknowledged it was "not an easy time" for the Menindee community and the federal government would provide assistance to NSW on request.

In a statement, the Murray-Darling Basin Authority's chief executive Phillip Glyde said the relevant governments were "doing their best" to manage the consequences of the drought.

"The main causes of this distressing event are the lack of water flowing into the northern rivers, and the impact of 100 years of over-allocation of precious water resources throughout the entire basin," he said.

"Without more water available to flow through the system, it is possible more fish will die during summer."

Mr Blair said future water releases from the Menindee Lakes would need to be managed "strategically", but it was too early to draw concrete lessons or commit to policy changes.

"There's no silver bullet," he said.

The Minister also rejected complaints from locals who accused him of snubbing farmers, elders and residents who had gathered at a boat ramp on the Darling River to discuss the tragedy on Wednesday.

Mr Blair said he met with locals and councillors elsewhere during his trip but was advised against stopping to speak with the group of up to 150 protesters due to security "threats".

In the video, Mr McBride claimed the fish kill had "nothing to do with drought".

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"This is a man-made disaster brought to you by the NSW government, the federal government and the Murray-Darling Basin Authority," he said.

Mr McBride's daughter Kate said the endangered Murray cod, which can live for decades, "have survived many droughts, and the highs and lows of it all, but the one thing they haven’t been able to survive is this mismanagement".

Earlier this week, Richard Kingsford, director of the Centre for Ecosystem Science at the University of NSW, said increased draining the Menindee Lakes made this type of disaster more likely.

"It's a classic example of nature biting back," he said.