The killer whale from 'Blackfish' is dying

Killer whale Tilikum watches as SeaWorld Orlando trainers take a break during a training session at the theme park's Shamu Stadium in Orlando, Fla on March 7, 2011.

The killer whale made famous by the award-winning documentary Blackfish is dying.

SeaWorld announced on Tuesday that Tilicum's health is beginning to deteriorate. He is becoming "increasingly lethargic" due to a bacterial infection in his lungs that the company says is "very resistant to treatment."

Veterinarians have failed to find a cure for Tilicum, the company said, and so their focus is now on keeping him comfortable and creating an "enriching life."

“It has been our duty and passion to make sure we give him the utmost care we possibly can,” said Daniel Richardville, a SeaWorld Animal Training Supervisor, on the company's website.

The news was met with a mixed response on Twitter. Some were sorry to hear that the animal is sick, but most were angry at SeaWorld for letting his health degrade to this degree.

The 34-year-old male orca has been in captivity at SeaWorld for the past 23 years. He was born in the wild and caught somewhere off the coast of Iceland in 1983.

The whale was spotlighted in the 2013 documentary as a stark example of the company's mistreatment of its animals, as well as what the filmmakers said were dangerous workplace practices.

Tilicum, the film revealed, had killed three people — a trainer at a park in British Columbia, SeaWorld trainer Dawn Brancheau and a trespasser who broke into the Orlando facility after-hours. Blackfish speculated that he had gone psychotic as a result of being held in captivity.

SeaWorld denied this, but animal rights activists who saw video of Tilicum floating in place or swimming mindlessly in circles have concluded that the whale has suffered from undisclosed health issues.

Today's statement seems to confirm this, suggesting that the whale's health issues are not new. "Despite the best care available, like all aging animals, he battles chronic health issues that are taking a greater toll as he ages," SeaWorld said.

If the whale ultimately dies from the infection, his death would continue a depressing streak for the embattled company, which saw three whales die in captivity in 2015 alone — all at SeaWorld San Antonio.

Unna, a female orca, died there in December of what the company said was a "resistant strain of a fungus called Candida." The other two deaths, which occurred in July and November, were young Belugas.

SeaWorld officials said the deaths were unrelated, and were not caused by stress or chlorinated water. In all the cases, veterinarians said they did what they could but ultimately couldn't save the whales.

“We were all saddened by these deaths, especially the animal care team that spent countless hours caring for these animals,” one SeaWorld official told theNew York Daily News after the third death. “After a review of each of these cases, none of the issues were related to each other, or to the care that the animals received.”