![Fiona rests her chin on the rim of a tub in her enclosure.](/web/20170327231809im_/http://www.smh.com.au/content/dam/images/g/v/6/i/m/3/image.related.articleLeadwide.620x349.gv6ipk.png/1490441220562.jpg)
The Cincinnati Zoo says its premature baby hippo, Fiona, is getting more independent and now tops 45 kilograms, meaning her days of napping on her human caretakers' laps are dwindling.
She was born at the zoo in January and weighed just 13 kilograms, far below the typical weight.
![Fiona bathes in her enclosure at the zoo.](/web/20170327231809im_/http://www.smh.com.au/content/dam/images/g/v/6/i/m/2/image.related.articleLeadwide.620x349.gv6ipk.png/1490441220562.jpg)
The zoo says caretakers raising Fiona are beginning to scale back their time with her, leaving her alone for a few hours at night.
It's the beginning of a transition into how much contact they have as they move towards eventually integrating her into a group of hippos with her parents.
They say hippos can grow to be 1360 kilograms and are very dangerous.
So at some point the caretakers will begin interacting with her only from behind a protective barrier.
Fiona is the first Nile hippo born at the zoo in 75 years.
Water play is an important form of exercise for Fiona, the zoo says.
![Wendy Rice, the zoo's head keeper of Africa, feeds Fiona from a bottle.](/web/20170327231809im_/http://www.smh.com.au/content/dam/images/g/v/6/i/m/1/image.related.articleLeadNarrow.300x0.gv6ipk.png/1490441220562.jpg)
She has learnt how to go up and down the ramp to her smaller water tub all by herself.
Hippos have the unique ability to sleep under water, raising their nostrils above the surface for a breath without waking, the zoo says.
AP