"I am quite pessimistic about the fate of these whale sharks," said Hua Ning, a campaigner at the International Fund for Animal Welfare in Beijing. "This aquarium only wants to make a profit and are using these creatures as a publicity gimmick. The whale shark is the largest fish in the world, and it needs a vast area of ocean to swim in.

Keeping them in a tiny space will put a lot of pressure on them and there will be corresponding consequences." Xiao Bing, an environmental activist in Xiamen, added: "In other countries, they prefer to take visitors out to sea in order to see large whales and fish. This is a low-cost way of enjoying nature, and mainland investors should look at this industry. But at the moment, the big companies and the government just focus on promoting tourism and making money."

Until now, only a handful of whale sharks have been kept in aquariums, and they have rarely fared well. In 2007, two young males died at the Georgia Aquarium within five months of each other.

A study of 16 whale sharks kept at the Okinawa Expo Aquarium between 1980 and 1998 found they only lived for an average of 16 months in captivity. By contrast, the fish often live for up to 70 years in the wild.

"Do the operators have qualifications to give these whale sharks appropriate care?" asked Ms Hua. "The problem is that we do not have any ocean animal protection laws in China," she added.

A spokesman for the aquarium, which forms the centre piece of a multi-million pound spa, hotel and leisure complex in Yantai, said: "We kept a whale shark alive for more than three years at another aquarium in Dalian, so we have confidence and experience.

"We have five aquariums across China and we wanted something a bit different for this one to boost the interest of tourists. I cannot say where we got the whale sharks from, or how much they cost, but in China we do not regard them as an endangered species."

The International Union for the Conservation of Nature classifies whales sharks as "vulnerable" and there has been a furore in the past when aquariums in Dubai and Singapore considered keeping the fish in captivity.

The number of aquariums in China has more-than-quadrupled in the last 15 years as the tourism industry has boomed. Conservationists have accused them of robbing the world's oceans of rare fish in order to thrill visitors, and at least 60 beluga whales are now kept in captivity on the mainland.