The zoo announced on Halloween that Henry the hippo died following a battle with an infection

The Halloween fun at Cincinnati Zoo & Botanical Garden has been darkened by tragic news.

On Tuesday, the zoo announced that 36-year-old Henry, Fiona the baby hippo’s dad, has died.

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“After watching Fiona fight, defy the odds and literally make history, it feels especially unfair and defeating to have to accept this outcome for Henry. While our time with him has been short in quantity, no one can deny that his quality of life before becoming ill was exceptional. From meeting, bonding and breeding with his mate Bibi, to becoming a father to charismatic and spirited Fiona, Henry’s days in Cincinnati were filled with sunshine, watermelons, waterfalls and the highest quality of care that can be provided to any animal,” said Wendy Rice, Africa Head Keeper at the Cincinnati Zoo said in the zoo’s statement on Henry’s death.

This announcement follows months filled with health struggles for the large male hippo, who lost hundreds of pounds leading up to his death. On Oct. 10, the zoo first shared on Twitter that Henry wasn’t feeling well.

“Henry’s had a rough week — still little appetite & is losing weight. Our care team is doing everything to help him. Please send good vibes,” reads the first post about Henry’s declining health.

Over the following weeks, Henry went to several vet exams, leading to sporadic closures of the hippo exhibit. The 3500-lb. hippo’s initial blood tests showed he was fighting an infection. The zoo responded by administering antibiotics and making sure Henry got the rest and care he needed in his weakened state.

On Oct. 20, Henry’s health appeared to improve. The zoo Tweeted that Henry’s infection and abnormal kidney function, which keepers feared wasn’t treatable, had been responding to treatment and medication.

Unfortunately, Henry’s spunk and fight wasn’t enough to pull him through. Over the past few days, Henry’s health started to decline again. After examining Henry Tuesday morning and determining that the hippo would not recover from his infection, zoo vets made the painful decision to euthanize Henry.

“The blood work from Henry’s last exam gave us some hope that he was on the mend, but his appetite never returned and his condition declined rapidly. Vets and his care team worked tirelessly to keep him comfortable and help him fight this illness. Nothing – antibiotics, favorite foods, extra TLC – seemed to turn his condition around,” said Christina Gorsuch, Cincinnati Zoo’s Curator of Mammals. “We are all so sad to lose him. Everyone loved him. He was a sweet, gentle giant with a big personality. He enjoyed interacting with his caregivers.”

This is a difficult loss for the zoo and #TeamFiona — the large group of Fiona the baby hippo fans who’ve fallen in love with the premature calf and her family over the past 10 months.

Keepers believe that Fiona and Bibi will be fine on their own without Henry, but that they surviving family members will likely notice Henry is gone and wonder why he isn’t answering their “Contact calls.”