Norton, one of the Georgia Aquarium's original whale sharks, died early this morning, after the aquarium euthanized it after months of strange behavior and illness.
"During the last few months, Norton stopped eating and started showing erratic swimming behavior," Jeff Swanagan, president and executive director of the Georgia Aquarium, told ABC News.
Swanagan said that exhaustive diagnostic tests had been conducted by husbandry and veterinary staff and that the team had been encouraged and hopeful Norton's condition would improve.
On Tuesday, caretakers noticed a marked shift in the giant fish's swimming behavior and blood work confirmed his decline in health.
In a statement, Swanagan said that a 24-hour watch had been put in place and that early this morning, Norton had stopped swimming and settled to the bottom. After every option had been exhausted, the team decided to humanely euthanize Norton.
In January, Ralph, another whale shark, died. A necropsy showed that peritonitis, an inflammation of the membrane that lines the abdominal cavity, was the cause of death. The aquarium husbandry and veterinary team are investigating multiple theories for any links between the deaths of the two animals.
At the time, handlers noticed that both Ralph and Norton had stopped eating within a few days of each other. Scientists attribute this loss of appetite to a series of treatments used in 2006 to manage parasites in the Ocean Voyager exhibit where the animals lived.
The aquarium team has not ruled out other theories.
"At this time, the exact cause of Norton's declining health is unknown. A necropsy will be performed and Norton's remains will then be cremated," Swanagan said.
The facility's remaining whale sharks, Alice, Trixie and two recent additions, Taroko and Yushan, are all said to be eating well.