The striped catfish Pangasianodon hypophthalmus is an important freshwater fish cultured in many countries where the collection of wild brooders is still widely practiced. Global farming development of this species makes use of significant natural resources that pose challenges for the genetic diversity of striped catfish. Hence, this study aims to conduct a systematic genetic diversity assessment of wild and farmed catfish stocks collected from four major pangasius-farming countries, using a new genotyping by sequencing platform known as DArT-seq technology. Our population genomic analyses using 7263 single-nucleotide polymorphisms (SNPs) after high-quality-control showed that there were two distinct populations of striped catfish in the lower Mekong river: (i) wild catfish from Thailand and (ii) catfish from Cambodia and Vietnam. The genetic diversity was greatest (0.363) in the wild stock from Thailand, but it was lower in farmed and wild stocks in other countries (0.049 to 0.088). The wild stocks were more genetically diverse than the farmed animals (0.103 vs. 0.064). The inbreeding coefficient ranged from 0.004 and 0.109, with the lowest value (−0.499) in the wild animals from Thailand. Molecular inference methods revealed high degree of historical effective population size (1043.9–1258.4), but there was considerable decline in the contemporary estimates in all populations (10.8 to 73.6). Our additional analyses calculating divergent times and migration patterns showed that the wild catfish from Thailand stand out as separate lineages, while those from Cambodia and Vietnam are genetically identical. Our results also indicated that the cultured stock in Bangladesh originated from the lower part of the Mekong river. These findings have significant practical implications in the context of genetic selection and conservation of striped catfish in the region. Collectively, they will contribute to the sustainable development of the striped catfish sector in these countries.

The genetic relationship of some Asiatic hard clam (Meretrix meretrix) based on mtDNA COI sequence analysis was investigated for populations collected in Thai Binh, Nam Dinh, Nghe An provinces in Vietnam. In addition, this research also targets at species identification based on COI sequences. In total of 59 sequences analyzed, 19 sequences belonged to Meretrix meretrix species with Gen Bank accession number DQ399399.1. 17 sequences of M. meretrix were used for genetic relationship analysis among 3 populations. In which, 6 polymorphic sites, 3 parsimony informative sites and 4 haplotypes observed for the COI gene. Moderately genetic population diversity was observed, overall haplotype and nucleotide diversity were 0.476±0.233 and 0.00151±0.00069, respectively. Generally, genetic differentiation (F ST ) (F ST < 0.15) was moderate. The genetic distance was rather low, which ranged from 0.001 (Thai Binh-NgheAn, Thai Binh-Nam Dinh populations) to 0.002 (Nam Dinh -Nghe An populations). The result of haplotype network constructing indicated that populations shared common haplotype and there was no specific isolation of the haplotypes of the populations. Hence, it showed M. meretrix populations had intimate genetic relationship. The result of phylogenic tree indicated that three M. meretrix populations (Thai Binh, Nam Dinh, Nghe An) had a very small or no genetic variation among populations.