Hippopotamuses are semi-aquatic animals with strong territorial instincts whose welfare in captivity requires deep water access, careful social management, and space to express their complex behavioral repertoire.
Hippo welfare in zoos is fundamentally determined by water quality and depth. Hippos that cannot fully submerge develop skin problems from their unique skin secretion (blood sweat) losing its moisturizing and UV-protective function. Territorial behavior in captive groups requires sufficient space for social avoidance and careful management of group composition to prevent serious injury from fights. Modern hippo exhibits with deep pools, land grazing areas, and appropriate social groups represent dramatically better welfare than the historically common shallow concrete pools. Their nocturnal grazing behavior means welfare-positive management may need to provide access to grazing areas after public hours.