Efficacy of DNA barcoding for the identification of larval fish species in the Upper and Middle Ing River, Thailand

DNA barcoding or the partial sequence of the cytochrome c oxidase I (COI) gene was employed for the identification of larval fish species collected between April 2017 and March 2018 at 12 stations in the tributaries of the upper and middle Ing River, northern Thailand. Seventy-six samples were successfully identified in the GenBank and BOLD databases at the species level; these samples were classified into 30 species, 25 genera, 14 families and 7 orders with 98–100% similarities. Only two samples could be identified at only the genus level, Rasbora sp. and Monopterus sp., because their COI sequences were not found in either database. The genetic distance within each species was very low, ranging from 0.000 to 0.005. The conservation status of most species was least concern (68.74%) followed by near threatened and data deficient (3.13% each). In addition, almost all species were used for either or all purposes, including fisheries, aquaculture and aquariums. Dermogenys siamensis was observed at all stations, and station 8 (Amphoe Dok Khamtai, Phayao Province) exhibited the highest number of larval fish species. The results of this study may be employed to support conservation efforts and determine the spawning grounds of larval fish in the Ing River. •DNA barcoding assists in identifying the larval fish species in the upper and middle Ing River, Thailand.•Seventy-eight samples could be classified into 32 species, 26 genera, 15 families and 8 orders.•Two genera could not be identified at the species level because their COI sequences were not found in any databases.•Some sampling stations are suitable to designate fish spawning grounds.