There has never been a recorded case of a wild orca killing a human, despite often coming within close proximity of each other, and welfare advocates have pointed to Tilikum's aggression as a sign of the stress and confusion of keeping whales in captivity.
Tilikum has also exhibited other signs of captive stress. He's been spotted floating motionless for hours on end - an unnatural behavior for orcas, who are constantly moving in the wild - and has broken off his teeth from chewing on the sides of his tank out of frustration.
Infections, like the one Tilikum is reportedly suffering from, are also more common in captive orcas than wild ones due to the stress of captivity and poor water quality.
But SeaWorld's kept a tight hold on Tilikum, who's at the center of their artificial insemination program; he's fathered 21 of SeaWorld's captive-born calves, only half of whom are still alive.
Hopefully Tilikum will pull through - but it's doubtful SeaWorld would have released this information if a recovery were in sight.
Tilikum's illness is just the latest in a streak of bad news when it comes to SeaWorld's animal health. Five marine mammals have died at the parks since last summer, including Unna, Tilikum's daughter, who passed away at just 18 from a reported fungal infection.