The youngster, who keepers have named Charlie, was born to the family of gentoo penguins at Sydney's Sea Life Aquarium last month, weighing just 90 grams.

But keeper Kiera Ponting says the little chick already weighs 3.5kg and is reporting well above average progress on the penguin chick growth curves.

"We think Charlie gets their love of food from dad, Pink Lady, who is one of the bigger penguins in the colony," she said.

"Charlie is also quite sassy but still very affectionate - just like mum Winnie.

"We can see this as Charlie regularly bows to its parents - which is an adorable sign of affection in penguin language," Ms Ponting said.

Visitors are mostly likely to spot Charlie running around after his parents in the sub-Antarctic penguin exhibit this summer.

The zoo is yet to reveal Charlie's gender.

Australian Associated Press