The Department of Fisheries have confirmed around 30,000 fish have mysteriously died in the Murray River over the course of the last week, and said the event was likely the cause of 'poor water quality'.
The number is a significant increase from the Department's initial estimate of 3000, and Recfishwest said it was likely the number would continue to grow.
The 'fish death event' triggered a warning from the department last Wednesday, and local anglers were advised to refrain from eating or handling any fish caught in the catchment while water and fish samples were collected and tested.
An investigation into the event was launched, and fish and water samples were collected for further testing.
Department of Water principal scientist doctor Tim Storer said the mass death was most likely caused by poor water quality due to low dissolved oxygen levels.
"Recent rains washed organic matter into the river and disturbed sediment that contains very little oxygen. These two factors resulted in dissolved oxygen falling below levels fish could tolerate," he said.