A video grab from Beijing TV shows a crab tied with a 31-meter string.

Crabs sold with 31-meter string accountfor 20 % of weight

In the following case, overwrapping a creature to be sold seems to be too much.

Some disgruntled customers report that they bought crabs tied-up with 31 meters of string during the past National Day holiday, BTV evening news said.

The water-sodden string, which was used to secure the crab's claws, accounted for 20% of its total weight.

However, this isn't the only scam you have to look out for on the local fish market. Last week, a restaurant in Qingdao was caught trying to trick customers by listing the price of shrimp dishes per shrimp rather than per dish. A man complained when his dish, with 40 shrimp at 38 RMB each, came to 1,520 RMB.

A video grab from Beijing TV shows the 31-meter string,that was used to fasten a crab's claws, in a pile on the floor.