One of the Georgia Aquarium's five prized beluga whales is gravely ill and his immune system remains weak, aquarium officials said.

Gasper, a 17-year-old male beluga, has been ill for several years and doctors recently diagnosed a potentially deadly infection.

The aquarium said Gasper's immune system does not appear to be getting worse, but that he remains very weak. Officials had said in October that his immune system was failing.

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The whale is being monitored around the clock and aquarium staff are working to make sure the whale has the medications, fluids and nutrition he needs, said Dave Santucci, the aquarium's spokesman.

Before being brought to Atlanta, Gasper and his tank mate Nico had been housed in substandard conditions at an amusement park in Mexico City. There, the whales' tank was located beneath a roller coaster.

Gasper was in poor health with numerous skin lesions when the new owners of the amusement park agreed to move the whales to Atlanta.

Aquarium veterinarians later discovered Gasper had the potentially deadly bone disease osteomyelitis, and he was taken off exhibit for treatment in April.

Hundreds of get-well wishes flooded the aquarium, many from schoolchildren who had become enchanted by the ghostly white whale, who spent much of his time swimming near his tank's big window, appearing to smile for visitors.

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