THE mystery surrounding the "thousands" of small fish that beached themselves at Buddina remains just that.
They were gone in less than 24 hours.
The Environment and Heritage Department, the Queensland Museum and an astronomer who knows about tides were all unable to explain it.
Buddina resident Susan Sheard took the photo of the washed up fish when taking a walk along the beach on Wednesday afternoon.
Ms Sheard, who has lived on the Coast for 10 years, had never seen so many fish washed up at the same time.
EARLIER: Thousands of fish beached at Buddina
"It was a super low tide and there were thousands of them," she said.
"Some of them were still alive, flipping around and I threw a few back in the water. But there were too many."
A Environment and Heritage Department representative said officers had inspected the beach between Kawana and north to the headland and found no dead fish.
"It is possible the incoming tide and strong north-westerly winds may have washed the dead fish away."
Queensland Museum's ichthyologist Jeff Johnson examined the photo sent from Ms Sheard and said it was "highly unusual".
"Deaths of this many of this type of fish are highly unusual for an open, ocean beach," he said.
He thought they were sardines, but couldn't be certain from the image sent to him by the Daily.
"Sardines are not usually part of trawler bycatch, so I could confidently rule that out," he said.
"However it is very difficult to speculate on what may have been the cause, especially without a site inspection."
Owen Benedick from the Wappa Falls Observatory ruled out tides causing the problem.
"King tides and really low tides are associated with a full or new moon, but it is not either of these at the moment.
"Whales and dolphins can get lost with solar events, but not fish. It has to be an environmental issue."
The Environment Department encouraged people to report suspected pollution incidents, including fish deaths, to the pollution hotline on 1300 130 372.
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