Transcript for Meet the Cincinnati Zoo's viral social media star Fiona the hippo
Ah! Hey cutie. Oh, my goodness. Splashing her way into the hearts and on to the screens of millions across the globe. She's precious. Fiona is a diva. She's a ham. Fiona the hippo. From premature baby to bonafide brand. Featured on merchandise and given her own ice cream flavor. Chunky, chunky hippo. And time magazine naming her person of the year. Fiona joining the ranks of animal celebs with massive social reach like Marty the dog 2 million Instagram followers and the nala cat with $3.5 million and April the Girard 56 last year was born and 14 million watched in one day. But hippos are not the cuddliest of animals how did the journey to stardom begin, in the womb, first hippo to be barn in the Cincinnati zoo for 75 years but almost didn't make it as her mother went to labor six weeks early, and weighed just 29 pounds. Typical weight is 55 to 120 pounds. She was little. She was placed into a ad hoc hippo NICU and put on IV and given round the clock care. The keepers and zoo staff fighting to keep the baby hippo alive. It was very touch and go at the beginning. Had to make it up on the fly didn't know what was in hippo milk had to milk the mom and have that analyzed. Her daily struggle documented on Facebook. Small moments becoming big victories. The world watching as she learned to stand. I can stand. I'm a big girl. How to swim. And even took her first steps. I became emotionally attached just like the rest of the world and a few times I really didn't think she was going to survive. But little one didn't just survive, she thrived. So to see her start crossing those kind of lines that we didn't even know she would ever even hit, and she just like gang busters, you know, she just blew everybody out of the water. And as she gr so did her following. Here's a six week old Fiona, stubbornly learning how to walk up and down a ramp. Theh tiny triumph viewed over 21 million times on Facebook she more than doubled the zoo's following. What's she eat every day. She is getting 3,000 milliliters of formula and now eating adult diet, grain, hey, loves lettuce, apples, squash and speshlg occasions watermelon and pumpkin are some of her favorites. She played perfectly to the camera. Hi. Strike a pose little one. Ah! A true diva in action. What's it like day in and out to see all of the people come from all over the world to see them. It still a mazes me, I thought the crowds would die down but still to this day when you let her out you hear the crowd going crazy when she comes back out. Fiona is a bright spot after a dark episode of the controversial killing of silver back after child had fallen into the enclosure, the scene, ten minutes of horror, the boy's mother watching helplessly from above. Oh, my god. Oh, my god. Then a critical calculation to shoot the 450 pound animal to save the child's life. This is the zoo's director. Last year was a tough year with his killing how's this changed the zoo? You know last year was a challenging time, particularly for the people who worked directly with horanbay because we work with the animals like we do with the pets, like we love our kids they love their animal so that was a hard time. But in 2017 baby Fiona changed the moment of the zoo record attendance up 23% zoo officials nicknaming it the Fiona effect. What is the Fiona effect. She's really represented hope and being safe on the brink and love. People love that animal. Fiona's under dog story providing rare common ground in a divisive year. Who can't get behind a sweet baby hippo. Her spirit of resilience resonating with the visitors who come to see her play. When she was premature I was diagnosed with breast cancer so me and her had a battle together. To me it was really excite zbrg little kids would write handwritten letters, Fiona I was premi too and I'm okay now and here's a picture of me on my soccer team, you can grow up and be a hippo. Her short story, she will be one next week, now being told in books. I've tried to see her more I saw her the media preview and Loy mind before she was on public display I lost all journalistic integrity and freaked out in front of the window. Fiona loves to play to the crowds and mom always joins in. There she is. Hi. Look at this. Today Fiona is happy, healthy and hefty. She's about 3,000 pounds the mom, and Fiona about 600. She's got a bright future ahead. Will have lots of fans and lots of lettuce maybe years down the road a young man in her future. We'll have to vet him strongly. For "Nightline" in Cincinnati.
This transcript has been automatically generated and may not be 100% accurate.