AUTHORITIES believe tropical fish getting stuck in a cold water current might have been a factor in the beaching of tens of thousands of fish along the East Coast.
Preliminary investigations have identified a species of leatherjacket fish that washed up at Bicheno, Scamander and Binalong Bay.
The species is usually found in more northern, warmer waters.
The Department of Primary Industries, Parks, Water and Environment received reports of three events between Friday and Sunday.
A department spokesman said yesterday that the reports indicated one species of fish and pathology staff were analysing samples.
He said that the leatherjacket was recorded as a schooling species and juveniles sometimes carried in large numbers into south-eastern Australia in currents and ended up washed ashore in large numbers.
"There have been reports of other species involved in the stranding and these are being investigated as to whether they are linked or coincidental stranding events," the spokesman said.
Break O'Day councillor John McGiveron, who is the Tasmanian Game Fishing Association president, said the fish had washed up along the coast from Seymour to the top end of the Bay of Fires.
He said in addition to the leatherjackets, species included flathead and one broadbill swordfish.
Cr McGiveron said the fish were mainly juveniles, excluding the highly valued, deepwater broadbill, a rare find in Tasmania.
"The fact they are coming up alive, as well as dead, is weird," he said.
"The concern that most people would have, is what has it done to the overall fishery?
"It's potentially quite serious."
Cr McGiveron said the problem might be more widespread than reported, because fish might be washing up in unpopulated areas.