Hippopotamuses in zoos require access to both deep water for thermoregulation and social groups for normal behavioral expression, with welfare challenges from their specific physical needs.
Hippopotamus welfare in captivity depends fundamentally on providing adequate water depth and surface area for their semi-aquatic lifestyle. Hippos that cannot fully submerge develop skin problems from their unique skin biology, and their thermoregulation depends on water immersion. Social housing requirements present management challenges since hippos can be highly aggressive - particular care is needed in group composition and introduction management. AZA-accredited facilities with large, well-filtered pools and appropriate social groupings can provide adequate hippo welfare, while facilities with inadequate water infrastructure cause ongoing physical welfare compromise.