The bloom has spread along the west coast – and closed two beaches for a time earlier this week…at Murvagh and Rossnowlagh.
Now fish farmers in Donegal Bay and further north to Mulroy, Sheephaven, Traweenagh and Lough Swilly could suffer.
The phytoplankton known as Karenia has destroyed anything from 20%, to 80% in rare cases, of stocks in shellfish farms with oyster beds worst hit.
Richie Flynn, of the Irish Farmers’ Association, said the 120m euro industry employing 2,000 people nationally has been let down by successive ministers and top civil servants.
“There’s nothing we can do about the algae, it’s like the weather. But this is not a new or unmanageable situation,” he said.
“It is to do with form filling. We fully understand the science but this is not about biology or cross contamination. You fill in the forms and send them in and they sit there.
“We need to clear the massive backlog of licence applications to give businesses the flexibility to move stock away from such blooms. We have members who have been waiting up to seven years for a response to applications.”
Lugworms have been killed, cockles and oysters are also falling victim and Rossnowlagh and Murvagh beaches were closed because of the amount of dead fish washed on to the beach, he said.
The bloom occurs naturally at sea in warm humid conditions.
It’s known as the red tide because of the colour it turns the water.