Hundreds of dead fish in Darling River

Hundreds of bony bream have been found dead in a weir pool on the Darling River in northwest NSW after a recent drop in temperature.

Hundreds of fish have died and others are showing signs of stress in a weir pool on the Darling River in northwest NSW.

The small fish kill affected hundreds of bony bream near Bourke and was discovered by the NSW Department of Primary Industries on Wednesday.

"Other bony bream are showing signs of stress," the DPI said in a statement.

Recent rainfall and a 10 degree temperature drop between Sunday and Monday may have contributed to the fish deaths, the DPI said.

Bourke Shire Council is working with DPI fisheries staff and the Environment Protection Authority to clean up the dead fish.