Hippopotamuses have specific aquatic and social needs that are difficult to fully meet in zoo environments. Understanding these needs guides evaluation of hippo welfare in captivity.
Hippopotamus welfare in captivity centers on the provision of adequate deep water pools and appropriate social groupings. Hippos are physiologically dependent on water immersion for thermoregulation and skin health — shallow pools that allow immersion but not full submersion compromise welfare. Social housing must reflect the species hierarchical water-access social structure while managing the significant aggression that can occur between males. Facilities that provide deep, spacious pools enabling full behavioral expression including swimming and social interaction achieve substantially better welfare outcomes than those with shallow or inadequate water features. Nighttime grazing opportunities using naturalistic land areas extend behavioral repertoire beyond water-based activities.