Samples are being taken after reports of a suspected outbreak of crayfish plague in the midlands.
Samples are being taken from the Clodiagh River in Co Offaly and the National Parks and Wildlife Service have been notified.
Water users in the catchment area, which is on the Laois/Offaly border near the village of Clonaslee, should ensure biosecurity measures are put in place to prevent spread of disease.
People are being urged to check equipment for plant and animal matter before leaving a site, and to clean and dry equipment when moving between locations.
Crayfish plague is a invasive disease that can decimate crayfish populations, causing 100% mortality.
The white-clawed crayfish is native to Ireland and is commonly found in many lakes, rivers and streams.
It is an important part of the river ecosystem as it is a grazer of plants and is food for otters.
