The Shedd Aquarium in Chicago has euthanized its Australian lungfish that is nearly 100 years old, the oldest zoo animal in the city and the longest among aquarium fish worldwide to live.

In an announcement, aquarium officials said the 4-foot-long, 25-pound “Granddad” died Sunday, Feb. 5 owing to “a rapid decline in quality of life associated with old age.”

The aquarium acquired Granddad in 1933 from Australia’s Sydney Aquarium. He was transported there with his mate in time for the World’s Fair that year.

“Granddad outlived several generations of caregivers … He seemed a permanent a fixture at Shedd as the terra cotta fishes that decorate the building inside and out,” the aquarium stated in an online obituary.

Elderly Fish Remembered

Granddad, representing a prehistoric species, had graced Shedd since three years after it opened to the public. The fish was said to be in its teens upon arrival there, making its age likely in the 90s or even beyond a century when it died.

Michelle Sattler, aquarium collections manager at the institution, said Granddad started to lose interest in food in the last few weeks. His condition worsened on Saturday when he showed signs of vital systems shutting down. It was then that experts at Shedd decided to euthanize the animal.

It is estimated that during his lifetime, about 104 million visitors had witnessed the languidly moving, spotted fish, which was able to breathe air. In the exhibit, there are three other Australian lungfish as well as another African lungfish soon to be shown on display.

In August, Cookie the Cockatoo from Brookfield Zoo, another well-loved zoo animal, also died from age-related health issues. It belonged to the zoo’s original collection back in 1934.

Lungfish’s Age, Sweet Memories

Granddad’s species, a protected one in Australia, can live to be more than a hundred years old, according to ABC. They maintain a single primitive lung and have lived for almost 400 million years. Fossils demonstrate that they have mostly stayed the same for over 100 million years.

This species is native to Queensland’s Burnett and Mary Rivers, with a tiny population moved to the Brisbane River back in 1895.

Australian researcher Tom Espinoza from Queensland has been harnessing technology to delve deeper into their secret life cycle, hoping to answer the question around Granddad’s age.

He pointed to the scale as the top sample he would want, but also thought some tissue in the body would assist in DNA analysis. Traditional methods that typically use ear bones, he added, would not be able to determine the lungfish’s age.

At any rate, Granddad’s death has stirred so many emotions and memories on social media. Nathan de Rover from Chicago, for instance, said that he and his wife were married in front of the fish’s tank, making him a witness to their love.

The couple’s friend, Michael, started to “marry” the couple and said, “Ladies and gentlemen and fish,” de Rover recalled.

“It’s beautiful, it really is one of the gems of Chicago,” he said of the Shedd.

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