Flood and heat: why millions of fish are dying in western NSW

Once the fish start to die, the decomposition further pulls oxygen from the water, exacerbating the problem. Photograph: Otis Filley/The Guardian

For tens of kilometres, millions of dead fish are floating in slicks along parts of the lower Darling-Baaka River, turning the water green and leaving a putrid smell around the small New South Wales town of Menindee.

The scenes come just four years after the area witnessed a series of mass fish kills with millions of native fish perishing, prompting an independent inquiry.