Is hippopotamus solitary animal

Answer 1

No. Usually, hippos live in family groups, usually a single mature bull with several cows and calves. It's actually closer to hippos being polygamists, like certain sects of Mormons. If you want to draw a human parallel.

Answer 2

Hippos live in pods, which are dominated by a male bull. Each bull reigns over a certain area of the river, and is very territorial. Although they live in pods and tend to huddle close in the water, hippos do not form special bonds with each other. The only exception is between a mother and her female calf. Within the pods, hippos segregate themselves by gender, and tend to huddle with other hippos of the same sex.