The Honolulu Zoo says one of the zoo's two female hippopotamuses, Rosey, was found dead Friday morning.
A necropsy is scheduled for next week to determine the cause of death.
The zoo now has one one female hippopotamus and no males. The hippo exhibit is closed indefinitely while Rosey's body is removed and zoologists will be monitoring and comforting the remaining hippopotamus during this traumatic time.
Rosey weight around 3,000 pounds and was 25 years old. National Geographic says the average life span for a hippo in the wild is 40 years.