'Granddad' was just a sprightly juvenile lungfish when he undertook a three-week trip aboard a ship from Australia to the United States in 1933.
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The Australian freshwater fish had been brought across the salty seas from Taronga Zoo in Sydney with another lungfish to wow crowds during the Chicago World's Fair in 1933-1934.
He was seen by more than 104 million people during his time in Chicago, according to Shedd Aquarium, who sadly told the world of his death on Tuesday.
The long-lived fish, aged in his mid-90s, was euthanised after his body began shutting down.
He is considered the longest-living fish in a zoological setting, Shedd Aquarium CEO Bridget Coughlin said.
"For a fish who spent much of his time imitating a fallen log, he sparked curiosity, excitement and wonder among guests of all ages who would hear his story and learn about the incredible biology that makes his species a living fossil and one of the oldest living vertebrate genera on the planet," Ms Coughlin said.
Australian lungfish are endemic to south-east Queensland, specifically the Brisbane, Mary and Burnett rivers, and are able to breathe aquatically using gills and aerially using a single lung.
In 1994, just over a decade after Granddad's mate passed away, four more lungfish were sent to the Chicago aquarium from Sea World on the Gold Coast to encourage a breeding program.
Griffith University Associate Professor and lungfish expert Anne Kemp had been called in to determine the sex of the selected four, which ended up being two boys and two girls.
While the mating program did not eventuate, Granddad did manage to gain a group of whippersnappers that likely kept him amused in his later years.
The Queensland fish are listed as vulnerable under the Environment Protection and Biodiversity Conservation Act and Professor Kemp, who has dedicated 40-odd years of her life to the "boring" animals, said their wild populations were dwindling due to issues with adult reproduction, largely caused by poor environments along the riverbanks and associated dams.
"When the environment is poor, the adults don't make good eggs...they don't develop well and most die within a few weeks of hatching," she said.
"The whole problem with recruitment (breeding) actually started during the drought in the (Brisbane) river but it has got worse because the floods made such a mess of the river that it hasn't really recovered.
"It is not much better in the Burnett and the Mary, it is very sad really."
Lungfish are also found in Africa and South America and are a lot "sleazier" than their Queensland counterparts, according to Professor Kemp.
"They are fast, sleazy predators, ours is a sleepy old thing," she said.
"Their biggest predators are people, most people know they are protected but sometimes you find one on the bank that is dead."
The lungfish have remained virtually unchanged over the past one million years, thanks largely to a relatively unchanged environment, Professor Kemp said.
"They have been lucky because they are so basic and boring and dull. Their environment hasn't changed that much," she said.
"They invaded rivers and became freshwater animals and if you live in river chances are you spend time in billabong and swamp and those environments haven't changed that much until recently."
Professor Kemp said it was likely the Australian lungfish population numbers have dwindled down to the low thousands.
"At the most there would be a few thousand, at the most," she said.
"We don't know how long the lungfish can live to, they can live to great age even in wild but that doesn't matter if there aren't any babies."
