Stone qi is passed off as Spanish mackerel, and the prices of the two differ greatly.

Many people have had this experience: when buying fish at a traditional market, faced with fish after fish lying on ice, every one looks the same, you cannot name them, and after eating them you still do not know where the fish came from.

Fish have a great many names; scientific names and Minnan (Hokkien) names differ greatly, and coupled with a lack of marine education, most people have never seen what a whole fish looks like. Taiwan's fish landing declarations do not, as in the United States and Japan, require a unified name for the traded fish species. Some unscrupulous fish vendors find a business opportunity in this loophole, passing off low-priced fish as high-priced fish, the most common case being "stone goby passed off as Spanish mackerel."

In the Spanish mackerel fillets and Spanish mackerel thick soup that most people like to eat, the Spanish mackerel is the Korean seerfish (Scomberomorus koreanus) of the genus Scomberomorus, and the "stone goby" is the thorn seerfish of the genus Scomberomorus, both belonging to the family Scombridae. Xu Chengyu, general manager of the fish company Yongsheng Ocean, says the wholesale market price of genuine Spanish mackerel is about 700-900 yuan per kg, but when sold in the vegetable market the fish is not sold whole; it is mostly cut into round slices and sold as fillets, and some unscrupulous operators pass off the similar-sized stone goby, which costs only 100-160 yuan per kg.

If it is processed Spanish mackerel thick soup, shark meat costing 50-60 yuan per kg may be used as a substitute, a price gap of as much as 11-14 times. "People may not want to eat shark meat, but they inadvertently eat it when eating Spanish mackerel thick soup."