Recently, a koi fish at the San Diego Zoo underwent a medical procedure, to remove masses from its body.

This week, just in time for the San Diego Zoo’s official reopening to the public on June 20, a 2-month-old male pygmy hippopotamus and his mother, Mabel, graduated from their maternity habitat to the larger main pygmy hippo habitat in the Lost Forest area of the Zoo.

Ever wanted to know how long a hippo can stay underwater? How they “dance” so gracefully through the water? Or how long they sleep?