Thousands of dead fish have washed up on beaches south of Port Neill on eastern Eyre Peninsula.
ABC News reports that the fish - leatherjackets - were found on the beaches towards the end of last week (start of March) all along the high tide line.
Kirk Gibbon from the Port Neill Caravan Park said it was almost impossible to walk along the beach without stepping on dozens of them.
PIRSA Fisheries officer Andrew Carr says that they have sent samples of the fish off for testing to determine the cause of the mass death.
Results should be received in the next day.