Some people may not embrace turning 50 but one of Perth Zoo's oldest residents, Cerro the Galapagos tortoise, has celebrated the birthday with vigour.

At more than 200 kilograms, Cerro is considered a youngster, with the oldest Galapagos tortoise on record thought to be around 175 years old.

Perth Zoo marked his 50th birthday on Monday with a specially created cake made up of some of his favourite treats, including watermelon, kiwi fruit, pumpkin and strawberries.

"These tortoises don't have a good sense of smell, so they use their eyes to find food," zookeeper Emily Trainer said.

"Anything red really gets Cerro's attention; he loves any brightly coloured foods."

Ms Trainer said Cerro was the less dominant of the zoo's two Galapagos tortoises.

Cerro's cake included watermelon, kiwi fruit, pumpkin and strawberries. ( Supplied: Perth Zoo )

"Except when there is food around — then he gets a bit of speed up to make sure he eats first," she said.

"Cerro tends to lead a peaceful, lazy life.

"When not spending his time eating, he enjoys a dip in his pond, a play in his mud wallow and he is also very smart, so we do training sessions with him as well."

Cerro was originally born at San Diego Zoo and arrived in Perth with his younger brother Sierra in 2005.

While he was celebrated for reaching his half century, he still has a long way to go in age and exploits to match another Galapagos tortoise found at the Californian zoo.

Diego, at 100, has almost single-handedly rebuilt his species' population on their native island, Espanola — the southern-most in the Galapagos Archipelago — after fathering an estimated 800 offspring.