Mother Petre gave birth succesfully to the male calf on Monday afternoon. Staff are not expecting any health concerns during an assesment on Thursday, when the calf will also be weighed.

It is Petre's fourth calf and first since she came to Melbourne from Taronga Zoo in 2012.

Melbourne Zoo wild sea precinct manager Justin Valentine said Petre had been attentive and gentle with the calf, which zoo keepers have been monitoring 24 hours a day on CCTV footage. 

"We've been giving them that time between mother and calf to bond which is important," he said.

Baby pygmy hippos typically weigh between 3-6 kg. Mr Valentine estimated Petre's calf weighed about 5 kg.

An adult pygmy hippopotamus typically reaches 70-80 cm tall and weighs around 250 kg, about a quarter of the size of a full-sized hippo.

It is expected Melbourne Zoo visitors will be able to view the baby pygmy hippopotamus within the next couple of weeks.

"It's still early days but we're cautiously optimistic," Mr Valentine said. "It's been feeding well, mum has been allowing it to suckle."

Mr Valentine said Petre won't be too distressed when keepers come to check on her baby, as pygmy hippos in the wild tend to stash their young in bushes when they look for food.

"We'll assess her as well for any issues and then give her a swim so she can relax in a nice warm pool," he said.

The successful birth of the pygmy hippo was a big moment for the keepers at Melbourne Zoo, Mr Valentine said.

"It's the highlight of a lot of our careers. It's certainly my highlight," he said.  "We're getting pretty tired now but everyone is still on a high."

The calf should be able to swim from birth, Mr Valentine said, however keepers will slowly introduce it to water before putting it in the enclosure.