Auckland Zoo has put down its lions Zulu and Malik.
The half-brothers, who were born at Auckland Zoo just weeks apart in 2004, spent much of their lives at Wellington Zoo.
Zulu had suffered deteriorating mobility that medication couldn't slow, and Malik recently started showing similar symptoms.
Keepers believed Malik would struggle without Zulu and couldn't be moved to another facility.
The brothers returned to Auckland Zoo in 2018, after Kura, 19 and daughter Amira, 17, also had to be put down.
"My team and I loved these beautiful boys’ natures and watching the bond they shared with each other, as we know so many of our visitors did too, and we will miss them greatly," carnivore team leader Lauren Booth said.
Recently, Wellington Zoo put down its elderly lionesses Djane and Zahra.
Auckland Zoo says it plans to work with lions again as part of an Australasian breeding programme.