Dead fish stuck to the soles of children's feet.
That's how the kill of over 1,000 fish in Lough Sheelin was detected at the weekend.
The fish were flushed down stream to Crover where children and adults swimming in the lake discovered what was happening and reported it to authorities.
Inland Fisheries Ireland has begun an investigation into the matter.
Meanwhile, Lough Sheelin Trout Protection Association's Eamonn Ross says it will take years to restock that section of the river.
"Cray fish take a long time to recover so do trout," he continued.
"So you are talking about years before that river will recover.
"We seem to accept that fish kills and pollution incidents like this are acceptable.
"And it seems to me that we have lost our sense of outrage at stuff like this happening.
"This should not be happening."