Melbourne Zoo's newborn penguins, Wicket and Nippet, have lived up to the stereotype that babies can be picky eaters.
Keepers on Thursday continued training the cute chicks to respond to whistling - which signals the start of breakfast, lunch and dinner - ahead of their public debut in coming weeks.
But the pair of little penguins - the world's smallest species - are reluctant to try any fish other than their favourite finned food, pilchards.
Wicket and Nippet, who have different parents, are scoffing down 12 to 15 of the small creatures a day as they bulk up to join the zoo's popular main colony.
The boy-girl pairing - Wicket, an eight-week-old male, and Nippet, a six-week-old female - are also being weighed weekly to monitor their development.
Zoo staff used DNA testing to determine the genders, which can otherwise be difficult to distinguish in newborn nestlings.
The tiny duo's journey to adulthood was almost complete, Melbourne Zoo penguin keeper Kristie Lawrence said.
"Eventually our chicks will fully fledge," Ms Lawrence told reporters.
"They're pretty fluffy at the moment (that's) their baby feathers. They are starting to lose those and get their adult feathers."
Melbourne Zoo's class of 2017 is set to grow again in the near future, with some extra school friends for Wicket and Nippet on the way.
"We have two other eggs that are yet to hatch," Ms Lawrence said.
"Soon we'll be able to see those babies hatch and they'll eventually go through the same process."