Wellington Zoo's 20-year-old sumatran tiger was euthanised today.

Rokan the tiger's health recently deteriorated, said general manager animal care and science Mauritz Basson.

"Our zoo keepers and veterinary team have been monitoring Rokan's health closely over the past few years and he began to show signs of age, which were affecting his mobility," Basson said.

"Rokan has had regular medical examinations and we were able to manage his arthritis with pain relief and anti-inflammatories, but his lameness has increased over recent months.

Rokan the Sumatran Tiger was 20-years-old when he was put down. Photo / supplied
Rokan the Sumatran Tiger was 20-years-old when he was put down. Photo / supplied

"Close observations over the past month showed that he was no longer able to move comfortably and easily. The welfare of our animals is paramount, and the observations showed we were no longer able to sustain his quality of life, so the decision to euthanise Rokan was made today.

"Rokan has been much loved by his carers and other zoo staff over the past 20 years. He has also always been popular with our visitors who seem to have a real love for tigers."

Rokan has been at Wellington Zoo for 20 years. His mother Cantik bore two litters of cubs, which have lived in zoos around Australasia. Rokan was one of her first cubs, and Cantik's legacy has been important for the regional breeding programme for sumatran tigers.

"Rokan was a bit of a charmer with the female tigers, and would get away with sneaking up on them to give them a fright," said carnivore team leader Paul Horton, who has worked with Rokan over the past 14 years.

"Like lots of cats, he could be sneaky and playful - but he also had a relaxed side," said Horton.

"While he was always keen to get involved with training, he would always let you know when he had had enough."

Fewer than 400 sumatran tigers are left in the wild. The critically endangered animal faces grave threats from habitat destruction, poaching and illegal hunting. Large areas of their habitat are cleared to make way for large unsustainable palm oil plantations in southeast Asia.

"Rokan has helped so many people find a connection with tigers to understand the threats these animals face in the wild," said Horton.