It would be a common sense to have a fear of hippos so a phobia of hippos would be very unlikely. Hippos are the number one human killers among the mammals and they are very aggressive animals. They are also the most dangerous animals in Africa (after mosquitoes). read more
More to the point, there are two possible approaches to coining a term for "fear of hippopotamuses": one which places more weight on quick understanding by way of common terminology q.v. "homophobia", and the other which places the weight on clever construction and knowledge of arcane vocabulary q.v. "ailurophobia". read more
The word hippopotamus literally means "riverine horse" in theoriginal Greek. "Hippos" means "horse" and "potamios" means "river"or "rushing water". read more