A major fish kill is being investigated on the River Ilen in Skibbereen.
Fisheries Officers were alerted to the incident following a call from a member of the public early yesterday morning of Wednesday.
Officers estimate that there were around 2,000 fish mortalities across several species including sea trout, salmon, eel and flounder.
Fish mortalities were detected over a 2 kilometre stretch of the River Ilen, downstream from the centre of Skibbereen town.
Water and fish samples were taken from the scene by Inland Fisheries Ireland Officers and removed for scientific analysis at an independent laboratory.
Investigations are ongoing and Inland Fisheries Ireland is not in a position to comment on the cause of the fish kill at this stage, pending further analysis of samples taken.