Henry the hippopotamus has died after months of declining health. We are all heartbroken.

Henry is best known as dad to Fiona, the Cincinnati Zoo and Botanical Garden's famous hippo baby, who was born prematurely in January.

We’re very sad to announce that our beloved Henry has died. Read more: https://t.co/3cx5vSMzWF pic.twitter.com/dAX2a4YQIa — Cincinnati Zoo (@CincinnatiZoo) October 31, 2017

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In July, Henry, who was 36 years old, began suffering from what caretakers believe was an infection. Despite treatment, Henry lost hundreds of pounds. Over the last few weeks, he grew "weaker and weaker," according to a post on the zoo's Facebook page.

“After an exam this morning, vet staff determined that Henry’s quality of life would not improve and made the difficult decision to humanely euthanize him,” the zoo said in the post.

"Regardless of the cause, Henry had lost too much weight to bounce back," veterinarian Jenny Nollman told radio station WVXU. "He was weak and starting to become disoriented. There was nothing else we could do for him."

The zoo said in a tribute to Henry that he'd become "smitten with Bibi, the Zoo’s 18-year-old female, and followed her everywhere. The two were put together when Hippo Cove opened in July of 2016, and Fiona came along soon after.”

Even when he wasn't feeling well, Henry still "dutifully following Bibi around like a lost puppy," the zoo said inan earlier blog post.

Henry, Fiona and Fiona's mother, Bibi, made a charming family, whose playful and loving interactions drew fans from around the world. Those same fans are now grieving Henry's death.

RIP Henry the Hippo. Your legacy will live on through your spunky and life-filled daughter Fiona. My heart breaks for the hippo family @CincinnatiZoo — Hannah Richards (@herichards2016) October 31, 2017

“We are all so sad to lose him," Christina Gorsuch, the zoo's curator of mammals, said to Cincinnati.com. "Everyone loved him."