The chance of further fish kills in NSW remains high as a cool change moves across the state, the NSW Department of Primary Industries says.

The department on Friday confirmed up to 10,000 fish died at Redbank Weir on the Murrumbidgee River when cool weather earlier this week led to low dissolved oxygen levels in the water.

“The risk of further fish kills remains high as a cool change moves across the state,” the DPI said in a statement.

Murray cod, golden perch, silver perch and carp died on the Murrumbidgee.

There was also another mass death event on the Darling River at Menindee involving up to a million fish.

Four tonnes of dead fish were removed from the area with most being bony herring, golden and silver perch and some non-native carp.

“The clean-up contractor is now on standby,” the department said on Friday.

Authorities remain concerned about water quality on the Murrumbidgee at the Maude and Hay weir pools “and the potential for significant changes in air temperature to trigger further fish deaths”.