Abstract: The experiment was carried out during the 2003 to 2006 at the Department of Fisheries, Khon Kaen University, Khon Kaen, Thailand in collaboration with the Department of Biosciences, the University of Hertfordshire, College Land, Hatfield, Herts, UK. Molecular RAPD technique was used for the determinations of DNA patterns of the fish genus Puntius Hamilton 1822. The fish samples of 1,500 individual fish were collected from fifteen wetlands in Northeast Thailand and they were used for DNA extraction. Before the experiment was carried out the fish samples were morphologically identified and it was found that the collected fish consisted of 9 species i.e., Puntius altus, P. aurotaeniatus, P. binotatus, P. gonionotus, (e) P. leiacanthus, P. orphoides, P. partipentazona, P. schwanenfeldi and P. wetmorei. Genomic DNAs were extracted from 5 mg of muscle tissues (skeleton muscles) with the use of PUREGENETM DNA Isolation Kit for Laboratory Use, Gentra Systems, USA. Eighty decamer primers from four kits were subjected to a preliminary test. It was found that only 10 decamer primers were most suited for this PCR amplification. The results showed that genetic distant values being established among and between pairs of the fishes of the 9 fish species ranged from 0.191 to 0.456 for a pair between Puntius gonionotus and Puntius altus and a pair between Puntius schwanenfeldi and Puntius leiacanthus, respectively. Similarity coefficient values within the 9 fish species ranged from 0.109 to 0.231. The results on a Dendrogram of clusters showed that there were 5 minor groups of the 9 fish species but the 9 species could not be split or shifted into other genera of the fish due to small differences found within the values of similarity coefficients.