Image copyright Amanda Meehan

Thousands of small fish have been found washed up on a beach in County Donegal.

The fish were discovered at Downings beach on Saturday morning and the cause, so far, is a mystery.

A holidaymaker told BBC News NI she was shocked to find the fish during a morning walk.

"The lifeguard said he thought the high tide had washed them onto the beach, but no one has ever seen anything like it before," Amanda Meehan said.

Media playback is unsupported on your device Media caption The fish are strewn across Downings beach

Various possible causes have been suggested to BBC News NI including the tide and rough weather.

A storm overnight caused heavy rain and strong winds and waves, but that in itself is not unusual for Ireland's north west coast.

Others have claimed it is result of a red tide - a toxic microscopic algae that kills marine life. In 2012, it caused hundreds of dead fish to wash in Counties Donegal, Kerry and Cork.

Image copyright Amanda Meehan

One local man said fishermen in the area reported a pod of dolphins in the bay in recent days and he believes the fish were trying to escape from the dolphins.

He said the fish that washed up on Saturday morning all appear to be of the same species, which could discount the red tide theory.

Ms Meehan, from Londonderry, regularly stays in a caravan in the area and said she's walked along the beach every morning during her stay.

"This morning, it was just really bizarre. There were thousands of fish spread right across the beach.

"There were a few fish up near the sand dunes, which we thought was a bit strange anyway, but then, when we got onto the beach, we saw the rest of them.

"The whole beach is covered and nobody really knows why this happened."