Unlike many other fish where their eggs hatch in hours or days, it can take a month for a lungfish fry to emerge.

Recent research has found it has one of the largest genomes – the genetic information of an organism – in the animal kingdom; 15 times bigger than that of humans.

Knowing more about the lifecycle of the lungfish will help conservation efforts for the species which has seen its fragmented range confined to a 328-square-kilometre area of South East Queensland.

The species – which is listed as endangered on the International Union for Conservation of Nature red list of threatened species and vulnerable by federal authorities – occurs naturally in the Burnett and Mary rivers but has been introduced to other ecosystems in places like Brisbane.

As a river specialist, lungfish can be threatened by changes to their habitat through flooding, dams, declining water quality, erosion and sedimentation.

CSIRO molecular biologist Dr Benjamin Mayne, who was a lead author on the paper that revealed Granddad’s age and origin in the Burnett River, said lungfish were a key species, an indicator of the health of a river ecosystem.

He said working out the maximum age of a species was an important factor for determining extinction risk and population management.

“It works out mortality rates and whether or not, in the wild, the species are reaching their maximum potential,” Mayne said.

“Unfortunately for most species it is hard to work out their maximum age except for ones that have been in captivity.”

Seqwater ecologist Dr David Roberts, another author on the paper, said the research highlighted the kind of serendipitous chance discoveries that could come from public aquariums working with other institutions for species protection.

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The next steps in the research were to apply the model to age wild lungfish from across their range, to assess population dynamics and longevity patterns.

“We are also establishing a library of living lungfish that reside within various public aquariums and wildlife sanctuaries, that will enable Dr Mayne to recalibrate the lungfish ageing clock as these lungfish age gracefully and live beyond the current clocks maximum calibrated age range of 77 years,” Roberts said.

One lungfish scientists are keen to find out the age of is the female named Methuselah, after the biblical figure said to have lived to 969, who was taken from Australia to San Francisco in 1938 and resides at the Steinhart Aquarium.

Methuselah, the fig-loving fish, is believed to be about 90 and could be the oldest fish in captivity in the world.