In contrast to the well-known red crayfish in China, less common blue or white crayfish are causing food safety worries that may not be justified, news portal cnhubei.com reported.

Spicy crayfish and ice-cold beer are a popular combination on hot summer evenings in many parts of China.

The newly discovered blue or white xiaolongxia have been spotted in multiple provinces and cities, including Hubei, Jiangsu, Anhui and Chongqing. Many customers, hit by one food safety scandal after another in recent years, are concerned about the quality of the crustaceans.

There may be two causes for the emergence of the new xiaolongxia, according to Shu Xinya, a senior engineer at the Fishery Science Institute in Hubei province. They might have been introduced from abroad, or have simply changed color here in response to individual or environmental changes.

There are over 600 different types of xiaolongxia found all over the world. Blue and white versions are common in foreign countries, while red ones are the most common in China.

Despite the difference in appearance, it is safe to eat blue or white crayfish, says Shu. It is unlikely that their color is a consequence of environmental pollution or genetic variation.