An important and extremely rare wucai fish bowl, Longqing six-character mark and of the period. Photo Bonhams

LONDON - An important and extremely rare wucai fish bowl decorated with a bird theme – mandarin ducks, geese, swallows and crested egrets in the rippling waters of a lake - is estimated to sell for £500,000 to £800,000 at Bonhams sale of Fine Chinese Art in London on November 7.

The fish bowl – used as a magnificent vessel for keeping fish in the Imperial Court - is particularly important as it is one of only six known to exist – the other four examples are all in museum collections: The Sir Percival David Foundation at the British Museum, London; the National Museum of Scotland, Edinburgh; the Hatakeyama Kinenkan Museum, Tokyo; the State Museum of Oriental Art, Moscow; and the Umezawa Kinenkan Museum, Tokyo. It appears to be the largest of the five, measuring 57.2cm in diameter.

Asaph Hyman, Director of Bonhams Chinese Art department, comments: "This hitherto unknown artefact presents collectors and museum with a once in a life time opportunity to acquire what is without a doubt an extraordinarily rare and important relic of the brief Longqing reign period."

The bowl's decoration, ducks depicted with lotus symbolise a harmonious conjugal relationship. Geese, similarly to Mandarin ducks were believed to mate for life and therefore also symbolise peace and prosperity in addition to marital fidelity. Egrets amidst lotus represent the Confucian ideal of a virtuous official. The latter would have been deemed particularly pertinent given the Longqing emperor's attempt to reform the governance and purge corruption in China five centuries ago.

The bowl has been discreetly kept in a distinguished European private collection and was acquired by the present owners from a family friend in 1978, though it was known to them as early as the 1960s.

Imperial records note severe flooding and earthquakes in Jingdezhen in the area around the Imperial kiln in the late 1560s. In 1571 the kilns were devastated by fire. These elements caused significant disruption to porcelain manufacture at the time. Furthermore, the impressive size of the present fish bowl would have been difficult to fire and consequently very costly. In 1571 the Jingdezhen censor Xu Shi (1519-81) requested the large Imperial order recently sent to be reduced by 80 percent. He specifically asked that the large fish bowls should be entirely removed from the order as they were particularly difficult to fire. These natural disasters and disruptions to the Imperial kilns during this very brief reign period underline the rarity of surviving examples of this period.