The killer whale from award-winning documentary Blackfish is on the brink of death, SeaWorld revealed Tuesday. "We are saddened to report that over the past few weeks, Tilikum's behavior has become increasingly lethargic, and the SeaWorld veterinary and animal care teams are concerned that his health is beginning to deteriorate," the animal theme park said. "Our teams are treating him with care and medication for what we believe is a bacterial infection in his lungs. However, the suspected bacteria is very resistant to treatment and a cure for his illness has not been found." The company added that its veterinarians have turned their focus to "managing his illness in a way that makes him comfortable and creates an enriching life." The elderly orca has been at SeaWorld for 23 years and—as Blackfish made famous—he has killed three people, including two trainers, possibly as a result of the strain of captivity.