Authorities are investigating a mass fish kill off Coogee.
Several hundred scaley mackerel have been reported floating between the Woodman Point Ammo Jetty and the Omeo Wreck, some washing up on Coogee Beach.
Department of Primary Industries and Regional Development (DPIRD) officers are gathering samples to work out why they died.
People are reminded not to swim in areas of water with large numbers of dead and decomposing fish because they may contain high levels of bacteria.
It is also advised not collect or consume the dead fish.