At 92, the Lungfish Methuselah Is the Oldest Fish in Captivity

The Australian lungfish is a river fish native to southeastern Queensland. According to fossil records, the ancestors of this ancient fish appeared about 380 million years ago. As their name suggests, lungfish don’t just breathe with their gills, but also have a lung to supplement oxygen intake during unusual circumstances, such as when there is poor water quality, low water levels or during spawning season. Lungfish are the most closely related of any living creature to the first fish to crawl from the sea onto land.

One particular lungfish, named Methuselah, was taken from her native waters in 1938, along with 231 other fish from Australia and Fiji, and brought to San Francisco on a steamship, a press release from the California Academy of Sciences said. She was then transported to the California Academy of Sciences’ Steinhart Aquarium, where she has been all these years. Methuselah has since become the oldest living fish in captivity at around 92 years old.

Methuselah was previously thought to be roughly 84 years old. But now, using a new DNA method, scientists in Australia were able to test a small sample of her fins in order to get a more accurate estimate of 92 to 101 years old, reported The New York Times.

“Although we know Methuselah came to us in the late 1930s, there was no method for determining her age at that time, so it’s incredibly exciting to get science-based information on her actual age,” said Charles Delbeek, curator of aquarium projects at Steinhart Aquarium, in the press release. “Methuselah is an important ambassador for her species, helping to educate and stoke curiosity in visitors from all over the world. But her impact goes beyond delighting guests at the aquarium: Making our living collection available to researchers across the world helps further our understanding of biodiversity and what species need to survive and thrive.”

A study by Dr. David T. Roberts of Seqwater and Dr. Ben Mayne of CSIRO of more than 30 lungfish from the California Academy of Sciences and six other U.S. and Australian institutions will be used to create a living lungfish catalog in order to improve the accuracy of an earlier age clock based on DNA.

“For the first time since the Australian lungfish’s discovery in 1870, the DNA age clock we developed offers the ability to predict the maximum age of the species,” Dr. Mayne said in the press release. “Accurately knowing the ages of fish in a population, including the maximum age, is vital for their management. This tells us just how long a species can survive and reproduce in the wild, which is critical for modeling population viability and reproductive potential for a species. It is a rare and valuable opportunity for researchers to access exceptionally long-lived fish such as Methuselah kept in the care of California Academy of Sciences, as it helps us understand maximum longevity of a species under ideal care conditions.”

Figuring out the age of such long-lived fish can be difficult, but the new DNA method allows for more accurate, non-invasive samples that can be used to continuously update the age clock for lungfish.

“By aging living lungfish from across the world we are creating a library of living lungfish that will enable Dr. Mayne, and other researchers working on longevity of the vulnerable Australian Lungfish, to continually recalibrate the aging clock as new and older aged samples of lungfish become available. Methuselah’s age was challenging to calculate as her age is beyond the currently calibrated clock,” Roberts added. “This means her actual age could conceivably be over 100, placing her in the rare club of fish centenarians. While her age prediction will improve over time, she will always live beyond the calibrated age clock, as no other lungfish we know is older than Methuselah.”