Adelaide, Australia - An Australian zoo had sad news for all its visitors: its African lion couple Mujambi and Amani had to be put down in quick succession.

According to a Facebook post by Adelaide Zoo, the 19-year-old Mujambi suffered a medical incident last weekend.

Despite receiving the best care possible, he had to be humanely euthanized.

Just a few days later, the zoo decided to put down his closely bonded partner Amani as well.

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Mujambi and Amani had lived together for 16 years.

With such a closely bonded pair, the zoo felt that Mujambi's death would significantly deteriorate Amani's own quality of life.

All options for the lioness' continued life had been internally debated for a long time, but for her own well-being they did not want her to have to live without her partner.

Both animals had been under medical treatment for some time, mainly due to their advanced age. At 23 years old, Amani was actually the oldest lioness in Australia.

Zoo director Phil Ainsley described the relationship between the two big cats as "quite remarkable" to ABC News: "So incredibly bonded, and just amazing to see that relationship between two very social species."

Adelaide Zoo is now planning to be without lions for some time and wants to convert the enclosure of the deceased lion pair into an extended area for its Sumatran tigers.