"The Hippopotamus is one of the largest mammals on the African continent and although mature adults are much harder for predators to kill, they are still preyed up by a number of predators throughout the wetlands. Big cats such as Lions and other animals like Hyenas and Crocodiles are the most common predators of the Hippopotamus, particularly of the young or sick individuals. "

https://a-z-animals.com/animals/hippo/

this is elementary. not sure why i am getting downvoted

An adult hippo can easily kill a croc.

crocodiles tend not to eat hippos.

Nothing eat Hippos, a healthy adult has no predators.

I guess only man and other hippos can kill a hippo.