One of the Georgia Aquarium’s three beluga whales died suddenly Tuesday, a month after it was moved temporarily to Texas as a precaution while construction takes place at the Atlanta facility.

Nico, a 25-year-old whale, was one of three belugas moved last month to SeaWorld San Antonio to shield the whales from a noisy expansion of dolphin facilities near their 800,000-gallon tank in Atlanta. Animal health specialists said an initial gross necropsy on Nico was inconclusive.

“We’re all very sad and dealing with that right now,” the aquarium’s chief veterinary officer, Dr. Gregory Bossart, told The Atlanta Journal-Constitution. Bossart dismissed any notion that the move in a Fed Ex container was a factor in the whale’s death.

"Usually when you have problems as the result of a transfer, it happens in first few days,” he said. “And he’s been there for nearly a month."

In October, the Georgia Aquarium moved Nico and two other whales — Maris and Natasha — to Texas for the duration of a construction project that includes a major expansion to the aquarium’s dolphin exhibit, set to open in late 2010. (See the video at bottom for footage of the belugas at the Georgia Aquarium.)

Indeed, the aquarium, which bills itself as the world's largest, has taken pains to keep its belugas healthy since two others died in 2007. Gasper was euthanized because of a bone disease he had before arriving in Atlanta, and Marina died of old age. 

That year, the aquarium also lost two whale sharks, Ralph and Norton, who died after developing infections from a chemical used to treat their tanks. 

As a precaution, the aquarium’s husbandry department decided to move the belugas to Texas, away from the construction. Belugas are extremely sensitive to sound, and while they never showed signs of stress, aquarium staff decided the move was in their best interest.

SeaWorld in Texas has been dogged by its own whale deaths: 11 beluga whales have died there since it opened in 1988, The San Antonio Current reported.

Nico originally came to Georgia in October 2005 after being rescued from an amusement park in Mexico City, where he lived underneath a wooden rollercoaster in “substandard conditions,” Bossart said. At the time, the whale had stomach problems, liver issues and skin tumors.

Essentially, the beluga was “living on borrowed time,” Bossart said. "We rescued Nico knowing that he had health issues due to his prior home, but we were confident that we could provide a better quality of life for his final years."