The water was imported from Hawaii, a part of the United States, by Zhanjiang Dacheng Aquaculture Co. The seawater import was the first of its kind in the coastal city, said Yang Wei, an official with Zhanjiang customs.

The seawater will be used to accommodate larvae of more than 2,000 white-leg shrimp, also known as litopenaeus vannamei or Pacific white shrimp, imported earlier from Hawaii, said Wu Changde, general manager of the company.

The company imported the same species in 2008, but needed to add permissible chemicals to purify the local water and to help the larvae live, eat and digest.

"Local water and water from Hawaii are different, for example, in their mineral content," Wu said, adding the water, imported for a cost of 400,000 yuan ($60,000), is to ensure the output and quality of the shrimp.

The white-leg shrimp, if raised well, may annually bring in several million yuan in revenue to the company, which plans to import more of the species later this year.

The import posed a challenge to the Zhanjiang Customs workers, who, upon receiving the declaration application, started to search for information on seawater, consulting local aquaculture professionals, Yang said.

They asked other customs agencies for details on how to inspect seawater.