Hippos require extensive water access for thermoregulation and social behaviour, making pool size and quality central to zoo hippopotamus welfare.
Hippos deprived of adequate water access develop desiccation-related skin problems and significant psychological stress. Their large size, territorial nature, and high water requirements make hippo keeping genuinely challenging. Zoos that maintain hippos well require large, deep pools with space for multiple animals to avoid and retreat from each other. Small, shallow pools that force constant contact between incompatible animals cause chronic stress.