What is the diet of a hippo?

Answer 1

Plants. They're herbivores.

Answer 2

I was not sure what one you wanted so I posted both.

Hippopotamus

The hippopotamus is strictly a vegetarian. Its diet consists mainly of terrestrial grasses.
http://animaldiversity.ummz.umich.edu/site/accounts/information/Hippopotamus_amphibius.html

Pygmy hippopotamus

The pygmy hippopotamus has an herbivorous diet, eating fallen fruits, aquatic plants, grass, and leaves. Feeding usually begins in the late afternoon around 3pm and subsides around midnight. Pygmy hippos are able to feast in water and on land.
http://animaldiversity.ummz.umich.edu/site/accounts/information/Hexaprotodon_liberiensis.html

Answer 3

In the wild the Hippopotamus eats soft grasses and other low lying plants, aquatic and reed plants, leaves, and fallen fruits. While in the zoo, however, the hippopotamus eat a herbivorous diet. The hippopotamus will occasionally eat cultivated crops such as corn and sugar cane.

Answer 4

An adult hippo eats more than 150 pounds of grass a night. These grazers tear up grass not with their teeth but with their lips. In the zoo, they eat zoo ration, alfalfa hay, trace minerals, and water free choice.