There are probably only 2 living species:
Hippopotamus (Hippopotamus amphibius)
Pygmy hippopotamus (Choeropsis liberiensis or Hexaprotodon liberiensis)
The Malagasy hippopotamus (3 separate names) is believed extinct, along with another half dozen prehistoric versions from various habitats.
Hippos are indentified as vulnerable species in 2006 and the estimated numbers are 20,000 to 25,000
hippos pirannas macrels stingrays-many species pufferfish
Hippos are not related to horses at all. They are actually more closely related to whales and dolphins. There are three species of hippos.
Elephants, hyenas, zebras, hippos, crocodiles, lions.
A few fish have a symbiotic relationship with hippos. Some species keep the hippos free from dirt and parasites and in return, they get a free ride.
none
none
Only if they are very ill. NO THEY DONT EXIST!!!!!!!!!Your question falsely assumes that hippos are fat; in fact most hippos you see are quite normal weight for their species. Their body build is mostly muscle, and there is very little actual fat on them. It is guaranteed you have never seen an obese hippo.
2 and a half
300`000 are left
about 750,000 to 425,000
Hippos cause 2,900 deaths per year. Source: buzzfeed.com; oddeee.com