Inland Fisheries Ireland (IFI) says it is investigating the source of a serious fish kill in Co Wicklow in which early indications suggest up to 2,000 fish may have died.
The incident occurred on the Aughrim River, near Aughrim, Co Wicklow.
Fish mortalities were observed in a 3km stretch of the watercourse in an area near Coats Bridge.
Species of fish discovered dead include juvenile and adult Atlantic salmon, trout and lamprey.
IFI says it is not aware of the specific source of this harmful ecological event at this stage.
Water samples have been taken from the river to gather evidence.
IFI environmental officers have been at the scene since early on Sunday morning (28 July), having been made aware of an incident following reports from members of the public to its confidential phone line at 0818 34 74 24.
Monitoring and assessment of the impact of the incident will continue in the coming days to try to identify the origin of the fish kill, IFI adds.