Why Gerbils Bite
Most bites happen because of an identifiable cause, such as putting your hand into the tank during a gerbil fight, or picking up a gerbil that is badly stressed due to illness or fright. Occasionally, a gerbil will bite hard if it smells another gerbil on your hands. A gerbil who suddenly becomes a biter may be ill and in pain. If biting persists, especially if accompanied by other symptoms of illness, see a vet.