The oldest aquarium fish in the world has died, officials announced on Monday. According to Chicago’s Shedd Aquarium, the fish named Granddad the lungfish, was euthanized due to failing health.

Although the exact age of the lungfish was unknown, a spokesperson from Shedd Aquarium believes that Granddad the lungfish was in his mid-90s. He is the longest-lived fish in any aquarium or zoological sites in the world.

Granddad, which was originally from Australia, was one of the aquarium’s most iconic and popular residents. The aquarium also adds that Granddad the lungfish was found of leafy greens.

The aquarium in Chicago acquired the fish, along with another lungfish, from the Taronga Zoo and Aquarium in Sydney, Australia in 1933. During this time, the aquarium hoped that the fish would attract visitors that were expected to visit the “A Century of Progress International Exhibition,” held close to them.

These two lungfishes were actually the fist of their species to be presented in an exhibit in the US. The Shedd Aquarium says that since then, the lungfish has been seen by roughly 104 million visitors.

“It is incredible to know that over 104 million guests had the opportunity to see Granddad in our care and learn about his unique species over eight decades,” pointed out aquarium president Bridget Coughlin in a statement on Monday. “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.”

The aquarium explains that Granddad showed signs of rapidly declining health last week. They observed that it had little interest in food. Eventually, he stopped eating. Upon examination, it has been found that he was suffering from organ failure.

“Granddad lived a pretty relaxed life, enjoyed interactions with us, including gentle pats along his back, and loved to eat his leafy greens,” says Michelle Sattler, a collections manager who has taken care Granddad for more than 30 years. “But, worms were definitely his favorite and he would become quite animated on what became Earthworm Wednesdays, when they were dropped into his habitat – animated for a very slow-moving fish. We loved him. And he will be sorely missed.”

According to experts, lungfish have existed for more than 380 million years and they have remained unchanged for more than 100 million years. They can live up to 100 years old.

Read more:

Marlin Drags Fisherman Into Sea, Victim Treads & Survives

Damselfish Relocation on Great Barrier Reef: Why It Happens