DNA barcoding of commercially important catfishes in the Philippines

Abstract

Many species of catfish are important resources for human consumption, for sport fishing and for use in aquarium industry. In the Philippines, some species are cultivated and some are caught in the wild for food and a few introduced species have become invasive. In this study, DNA barcoding using the mitochondrial cytochrome c oxidase I (COI) gene was done on commercially and economically important Philippine catfishes. A total of 75 specimens belonging to 11 species and 5 families were DNA barcoded. The genetic distances were computed and Neighbor-Joining (NJ) trees were constructed based on the Kimura 2-Parameter (K2P) method. The average K2P distances within species, genus, family and order were 0.2, 8.2, 12.7 and 21.9%, respectively. COI sequences clustered according to their species designation for 7 of the 11 catfishes. DNA barcoding was not able to discriminate between Arius dispar and A. manillensis and between Pterygoplichthys disjunctivus and P. pardalis. The morphological characters that are used to distinguish between these species do not complement molecular identification through DNA barcoding. DNA barcoding also showed that Clarias batrachus from the Philippines is different from the species found in India and Thailand, which supports earlier suggestions based on morphology that those found in India should be designated as C. magur and those in mainland Southeast Asia as C. aff. batrachus “Indochina”. This study has shown that DNA barcoding can be used for species delineation and for tagging some species for further taxonomic investigation, which has implications on proper management and conservation strategies.

• Catfish
• COI
• DNA barcoding
• Siluriformes

Acknowledgements

We would like to thank John Carlos del Pozo, Ambrocio Melvin Matias, Jose Timothy Martin Chua and Jordan Ferdin Halili for assisting in collecting samples.

Declaration of interest

The authors report no conflict of interest. The authors alone are responsible for the content and writing of this article. We would like to thank the Office of the Chancellor of the University of the Philippines Diliman, in collaboration with the Office of the Vice Chancellor for Research and Development, for funding support through the PhD Incentive Awards (Project No 111105 PhDIA) given to J. P. Quilang.