The 17-year-old whale had been ill before arriving at the aquarium in October 2005, officials said. He and his tankmate Niko had been moved to Atlanta from an amusement park in Mexico City, where Gasper had developed skin lesions while living in a tank under a roller coaster.
His immune system was weak from chronic illness, including the bone disease osteomyelitis, and medical tests showed his health had deteriorated further over the past few weeks, the aquarium said in a statement Tuesday.
The aquarium's team of veterinarians "made the difficult decision to humanely euthanize the animal," according to the statement.
Hundreds of get-well wishes had flooded into the aquarium, many from schoolchildren enchanted by the ghostly white whale who had spent much of his time swimming near his tank's big window.
Georgia Aquarium chairman Bernie Marcus, said in the statement that he was saddened by the news, adding that, "We are comforted in knowing that Gasper received the finest care available in the year he was in the Georgia Aquarium."