Application of DNA barcoding in fish identification of supermarkets in Henan province, China: More and longer COI gene sequences were obtained by designing new primers.

In recent years, DNA barcode technology has been widely used in food identification, especially in the identification of fish. In China, there are few studies on the authenticity of fish products in Henan province of China. In this study, 179 fish samples were collected from supermarkets in Zhengzhou city and Xinxiang city in Henan province, China. COI gene sequences were obtained with PCR technology by designing specific primers and universal primers. COI gene sequences of all samples were obtained to identify species, which is used to investigate species substitution and mislabeling of the fish sold in the two regional markets. The molecular identification results showed that 28.49% (51/179) fish samples were not consistent with the labels. Substitution of high-price fish by low-price fish was prevalent. For example, halibut (Pleuronectiformes) and cod (Gadus) are replaced by striped catfish (Pangasianodon hypophthalmus), and some merchants label bighead carp (Hypophthalmichthys nobilis) as cod (Gadus), there are also accidental labeling errors (such as labels for greenfin horse-faced filefish (Thamnaconus septentrionalis) have been identified as grass carp (Ctenopharyngodon idella) and Wuchang bream (Megalobrama amblycephala) etc. Most of the samples labeled correctly are the fish of low economic value and the fresh fish. This study shows that almost all the commercial fish can be identified by COI DNA barcoding by newly designed primers. Finally, this study also gives a reference of real species of fish fillet in Henan province in China.