COI gene sequence method helps aquaculture farmers and their customers  

DNA sequence scrutiny has been used for over 30 years to aid in species identification. However, various sequences have been used for different taxonomic groups.  When using different identification tools, there is the potential for a high rate of exploitation.  The conserved sequence of the 5' region of the mitochondrial gene cytochrome oxidase subunit I (COI or cox1) was proposed as a platform for the universal DNA barcoding of life (Hebert et al., 2003).

Aquaculture farmers and their customers are faced with marketing issues relating to misidentification of the cultured fish species and the regulatory structure attempting to control movements of exotic fish.  For example, Department of Land and Natural Resources of State of Hawaii does not permit the fast growing tilapia, Oreochromis niloticus, for aquaculture, although there is some evidences that the genetic signature for this species exists in feral stocks collected from the wild throughout several Hawaiian Islands.  Misidentification problems have been reported for catfish in India, where at least seven distinct species of catfish have been sold under various common names.  This appears to be applicable to catfish marketing in India of fish species that are highly valued by consumers.  This study uses rigorous morphological comparisons confirmed by DNA barcode analysis to examine the level of substitution of clariid catfish, Clarias batracus by C. gariepinus in India.  Our results indicate that up to 99% of the market samples sold as Magur or C. batrachus were in fact C. gariepinus.