Molecular evidence for determination cryptic species of Indonesian swamp eel populations using denaturing gradient gel electrophoresis (DGGE)

Swamp eel is the Indonesian freshwater fish that should be understood and preserved due to their high economic potency in aquaculture. Additionally Indonesian swamp eel is commonly accepted to the species described as Monopterus albus (Synbranchiformes: Synbranchidae). However, the knowledge of genetic variation of this species from Indonesia is quite limited. Hence, in this study, we used the Denaturing Gradient Gel Electrophoresis (DGGE) and surveyed the genetic variation of cytochrome c oxidase subunit I (COI) in Indonesian swamp eels. Total of 300 samples of the swamp eel fish were collected from 15 populations in Indonesia. The DGGE results represented two genetic patterns (A and B) of the COI variations. In addition, the results revealed that five populations showed pattern A and six populations exhibited pattern B while four populations showed both patterns A and B of the COI variations. Therefore, the result supported the molecular data that the Indonesian swamp eel is a cryptic species complex. In addition, the distribution of swamp eel's COI patterns in Indonesia approves that DGGE is a rapid and sensitive method for the detection of a genetic variation of the fish.