Inland Fisheries Ireland (IFI) is investigating a "significant" fish kill in Cork in which early indications suggest at least 1,500 fish have died.
The pollution incident occurred on Ballybrack stream, a small tributary of the Douglas River flowing near Douglas village, Cork.
The dead fish are primarily brown trout, and European eels.
Fish mortalities were observed over a 1.5km stretch of the stream. Initial indications point to the possible entry of a chemical into the watercourse.
However, it is too early to definitively establish a pollution source.
IFI said it would like to remind the public to ensure household chemicals are used, stored, and disposed of in a "responsible manner".
Low water flow or increased temperatures are not believed to have been a factor.
An IFI Senior Fisheries Environmental Officer has been on site since early today to investigate the incident, which is believed to have occurred yesterday.
IFI said it will "continue to actively probe the cause of this harmful ecological event".
The agency was notified of the pollution by a member of the public through its 24-hour confidential hotline service.
IFI has urged the public to report instances of fish kills or water pollution to its 24/7 number.
