School of tropical Aussie fish wash up dead after swimming in cold waters

A large school of tropical fish have perished after finding themselves in cold Australian waters during their annual migration.

The threadfin leatherjackets, a species commonly found in tropical inshore marine waters, were found washed up along Tasmania's east coast.

Fisheries Tasmania (FT) said the fish was a "tropical species ... apparently at the absolute extent of their range" and had ventured too far into Tasmanian waters while travelling on the East Australian Current (EAC) and had died due to cold water.

"When the water cools or an upwelling of cold deeper water occurs, the tropical species struggle to survive," FT told the Australian Broadcasting Corporation (ABC) on Tuesday.

FT said the fish have been spotted further south in recent years as the EAC, which moves up to 30 million cubic meters of water every second, persisted further southward.

Mick Tucker, mayor of a local council near where the fish washed up, said beach-goers should not be concerned about the deaths.

"From all the reports I'm getting from locals, it's exactly the same as what's happened before," Tucker told the ABC.

"It doesn't happen every year but it's happened before and it's been proven to be a natural occurrence."

In a statement, the Integrated Marine Observing System (IMOS) said fish had washed up on the shores of Victoria and New South Wales as well.

"They started appearing on the beach in small numbers around March 11, but came in en masse in the last few weeks of March," IMOS said.

"Although most of the fish appear to be leatherjackets, there are also whiting, black sole, puffer fish, boxfish, sea urchins, flathead and even some penguins." Endit