HANGZHOU, Dec. 19 -- The whitening of the black eye circles of a panda at an eastern China zoo is likely caused by mites, and the condition is being treated, a zoo in Hangzhou City announced Thursday.

The Hangzhou zoo received a pair of panda siblings named "Chengda" and "Chengxiao" from the southwest province of Sichuan in September, both aged two years old.

Tourists noticed that the dark circles around the panda's eyes had disappeared and the fur had turned white. A picture was published online and sparked concern that the panda was sick.

Panda feeder Wang Lifen said that the color change was because the black fur of the panda, Chengxiao, had shed, possibly due to mites.

Chengxiao had shown similar symptoms while living at the Chengdu panda base, Wang added.

The base has offered therapy and the panda is in good condition, showing no symptoms of abnormality. "The treatment requires time, but fans don't need to worry," said Wang.