China welcomed its first authentic version of the giant Rubber Duck that has made a splash around the world and inspired fakes across the country.
But there were complaints that visitors had to pay to see it. The inflatable yellow bird by Dutch artist Florentijn Hofman -- which has made appearances from Australia to South America since 2007 -- attracted huge attention in China after photos of it bobbing in Hong Kong's Victoria Harbour.
The artwork soon took a commercial turn in China, with property developers setting up imitations in Hangzhou, Tianjin and other cities, that was criticised by the ruling Communist Party's mouthpiece the People's Daily.
After a few weeks the duck will shift to the Summer Palace, a tourist spot that also charges an entrance fee.
Expo official Qiao Xiaopeng said there were currently no plans to offer a free day but that the expo offered vast space to accommodate large numbers of visitors.
But the first crowds were small on Friday.
Kang Jing, 26, said she thought viewing the duck should be free, at least for Beijing residents.
"That would let more people come see it, which would be better," she said.
The duck was not completely inflated by the time of its debut, its beak somewhat limp and body tilting forward.
"It should be fatter and cuter," said Kang.
The duck looked smaller than she expected, Kang added -- even though the Beijing version was made to be 18 metres (59 feet) high, compared with 16.5 metres in Hong Kong.
A well-known restaurant, Quanjude, sought to take advantage of the installation by using it to advertise its own showpiece, Peking duck.
A sign at the expo entrance showed the artwork in a chef's hat with the words, "Come see the big yellow duck and eat a Quanjude duck burger".