Fisheries and Aquatic Sciences

A combination of morphological analysis and DNA barcoding (partial sequences of the cytochrome c oxidase I (COI) gene) was used to differentiate four gobiid fish species in the family Oxudercidae. Rhinogobius chiengmaiensis and Rhinogobius mekongianus were found in Thailand, while Eugnathogobius siamensis and Pseudogobiopsis oligactis were used for comparative purposes. Morphological identification relied on appearances, counts, and measurements. The 707-base pair COI sequences from eleven samples of four gobiid species were compared with reference sequences in public databases to confirm their scientific names. The average AT content was 51.8 ± 0.5% and the GC content was 48.2 ± 0.5%. Intraspecific genetic distances ranged from 0.00–0.28%, while interspecific genetic distances ranged from 0.86–16.63%. A neighbor-joining (NJ) phylogenetic tree depicted the relationships among the COI sequences of these species. Morphological analysis and COI sequences successfully distinguished the four gobiid species. Notably, the COI sequences of R. chiengmaiensis, R. mekongianus, and E. siamensis were previously unreported, hence, this study is the first report to add their sequences to public databases. These results can serve as valuable information for the management of aquatic resources, conservation, and aquaculture efforts.

Freshwater crabs are important biological resources in northern Thailand, yet their diversity remains poorly documented in many areas. This study investigated freshwater crab diversity in Ban Tham Subdistrict, Dok Khamtai District, Phayao Province, using morphological examination and mitochondrial cytochrome c oxidase subunit I (COI) DNA barcoding. A total of 69 specimens were assigned to four taxa. Indochinamon bhumibol and Sayamia bangkokensis were identified to species level, whereas two unidentified taxa were provisionally designated Potamidae sp. 1 and Potamidae sp. 2. Genetic diversity varied among taxa, with Potamidae sp. 2 showing the highest haplotype and nucleotide diversity, whereas S. bangkokensis showed no haplotype variation. Pairwise K2P distances revealed substantially greater divergence among taxa than within taxa. Phylogenetic analysis resolved the four taxa into distinct clades, while Automatic Barcode Gap Discovery (ABGD) recovered four molecular operational taxonomic units in the initial partition, corresponding to the four taxa. These results support the genetic distinctiveness of Potamidae sp. 1 and Potamidae sp. 2, although their species identities remain unresolved. Further taxonomic and molecular studies are required to clarify their identities. These findings provide baseline information for the conservation and sustainable management of freshwater crab resources in the study area.

A combination of morphological analysis and DNA barcoding (partial sequences of the cytochrome c oxidase I (COI) gene) was used to differentiate four gobiid fish species in the family Oxudercidae. Rhinogobius chiengmaiensis and Rhinogobius mekongianus were found in Thailand, alongside Eugnathogobius siamensis and Pseudogobiopsis oligactis. Morphological identification relied on appearances, counts, and measurements. The 707-base pair COI sequences from eleven samples of four gobiid species were compared with reference sequences in public databases to confirm their scientific names. The average AT content was 51.8 ± 0.5% and the GC content was 48.2 ± 0.5%. Intraspecific genetic distances ranged from 0.00% to 0.28%, while interspecific genetic distances ranged from 0.86% to 16.63%. A maximum likelihood (ML) phylogenetic tree depicted the relationships among the COI sequences of these species. Morphological analysis and COI sequences successfully identified the four gobiid species. Notably, the COI sequences of R. chiengmaiensis, R. mekongianus, and E. siamensis were previously unreported, hence, this study is the first report to add their sequences to public databases. These results can serve as valuable information for the management of aquatic resources, conservation, and aquaculture efforts.

Panprommin D, Sornphui S, Tipdacho P, Chaisan W, Tuncharoen S. 2025. Change of fish composition in the Nong Leng Sai Wetland, Thailand, after newly completed dredging. Biodiversitas 26: 2611-2621. The objective of this study was to explore changes in fish composition and fish species diversity in the Nong Leng Sai Wetland, Mae Chai District, Phayao Province, Northern Thailand, following the completion of dredging in 2023. Fish specimens were collected both in the areas of the Nong Leng Sai non-hunting area and in the Nong Leng Sai common properties area from February to December 2023. The results revealed the presence of 34 species, 31 genera, and 16 families, all belonging to 7 orders. Thirty-one native and three introduced species were found. A total of 561 individual fish were found with a total weight of 40,403.3 grams. The carp group was found in the highest numbers and with the heaviest weight: 325 individual fish, accounting for 57.9%, and a total weight of 29,462.7 grams, accounting for 72.9%, respectively. Fish were found in the miscellaneous group, where 177 fish were identified, accounting for 31.6% of the total, with a total weight of 5,876.4 grams, which represented 14.5% of the total weight. Smith's barb (Puntioplites proctozystron) was the dominant species in terms of numbers. In terms of threatened status, there were 28 species of Least Concern, 4 species of Data Deficient (Systomus rubripinnis, Clarias macrocephalus, Gobiopterus lacustris and Dermogenys pusilla), one species in Vulnerable (Wallago attu) and one species of Endangered (Pangasianodon hypophthalmus). The fish composition and diversity changed from what had previously been reported and were markedly different from those prior to dredging operations. It is necessary to continue monitoring fish diversity and composition after the dredging is complete, to gather information about changes in fish resources over time, leading to informed resource management based on accurate academic data.