DNA barcoding (a technology to provide rapid, accurate and automated species identifications by using short orthologous DNA sequences) has been fundamentally important in the past few years in system classification, molecular genetic diversity and species relationships of marine organisms as well as evolutionary relationships, and so on. The data set in DNA barcoding is obtained from a single specimen without regard to life stage or morphological characters of targets. Many times foreign scholars elucidated the impact of some predation on prey populations using DNA barcoding, nevertheless, we did less. Herein we introduce DNA barcodes, then discuss the relative merits in relation to the utility of DNA barcoding in identifying prey items of fish diets. The DNA barcoding shows promise in providing a practical, species-level identification tool that can be used for taxonomy and ecological studies, and many more.