Meteorologists in Japan are puzzled by a recent series of downpours - not heavy rain, but fish and tadpoles falling from the sky.

It all started in Ishikawa prefecture on the country's west coast when residents began to notice strange creatures lying dead in their gardens, on roads and in car parks.

"I found a dozen small fish on the footpath near my house," one man said.

Then about 100 tadpoles were found in the council car park.

Soon reports began flooding in about similar fishy downpours all the way from Hiroshima in the south-west to Iwate in the north-east.

One theory speculated that the creatures were sucked up by mini tornados or waterspouts and then deposited in towns and villages.

But meteorologist Mamoro Akita quickly put paid to that hypothesis.

Another theory suggests large birds such as herons or gulls have been dropping the fish and tadpoles mid-flight.

"It's possible these creatures were dropped by birds which scooped them up as prey," wildlife expert Tetsu Hayashi said.