It's been touch-and-go sometimes. The zoo even called a specialist from Cincinnati Children's Hospital Medical Center to insert an IV into Fiona's tiny veins when she was dehydrated.
But she's picked up 12 pounds in the last week, and she's bottle-feeding more often -- and eating more when she does. Zoo staff offer her a bottle every three hours or so, and she usually takes about three at a time.
Here's how the whole feeding routine starts: When she wakes up early from a nap, she wanders around the nursery, bumps her nose into bedding, stuffed animals and her caretakers looking for a bottle.
When keepers get ready to feed her, Fiona crawls into their laps and impatiently tosses her head up and down.
"A poorly timed kiss or cuddle could easily result in a fat lip for the care team, but it's a risk we bravely undertake in the name of conservation," the zoo said in a blog post Monday.
Fiona's nostrils and ears clamp down as she eats, a natural response for animals that often nurse underwater.
Then there's her little grunt: It sounds sort of like a pig (watch in the video player above).
After she's finished, she'll either pass out for a nap in the keeper's lap -- or toss her head up and down, sending the bottle and any leftover milk flying. The second response means she probably has enough energy for pool time, which means romping, rolling... and pooping.
Pool time also puts her closer to her parents, Bibi and Henry. Bibi has checked out her daughter's "pool antics," the zoo said, and Fiona paused and listened while her dad let out a huge bellow.
Still, Fiona spends about 18 to 20 hours a day sleeping -- something she prefers to do snuggled up with a keeper. That's pretty natural: Baby hippos in the wild often climb onto their mother’s backs to rest and sleep, which is safer than being between much larger adults.
While she sleeps, keepers clean up after her, disinfecting the nursery, her pool, and prepping her bottles.
"Additionally, our veterinary, nursery and nutrition staff meet constantly to reassess Fiona’s changing daily needs, making alterations and adjustments as required," Monday's blog post said. "Even communicating the daily changes to the 22 staff members involved in Fiona’s care is a large undertaking."
Fiona was the first Nile hippo born at the Cincinnati Zoo in 75 years. She weighed 29 pounds at birth, which is about 25 pounds lighter than the lowest recorded birth weight for her species. The normal range is 55 to 120 pounds.
On the most recent episode of "Hear Cincinnati," WCPO.com's Maxim Alter talked one-on-one with Dr. Jessya Wojtusik, a member of Fiona's care team at the Cincinnati Zoo. Listen below (interview starts at about 13:45):