Indonesia, home to a significant portion of the world’s fish biodiversity, faces challenges in accurately identifying and conserving its freshwater fish species, including Ompok hypophthalmus. This study examines the morphological and molecular identification status of O. hypophthalmus, highlighting inconsistencies in taxonomic practices and the need for integrative approaches. Morphological studies, such as those by Ng (2003), identified three distinct species within the O. hypophthalmus group, yet subsequent research often misclassified O. rhadinurus and O. urbaini as O. hypophthalmus. Molecular analyses, including DNA barcoding of cytochrome oxidase I (COI) and cytochrome b (Cyt b) genes, revealed significant genetic divergence among populations from different Indonesian rivers, suggesting speciation or misidentification in prior studies. Phylogenetic and genetic analyses confirmed the presence of O. hypophthalmus in Arut River, while Indragiri and Tapung Rivers were dominated by O. rhadinurus. These findings emphasize the importance of integrating morphological and genetic tools to resolve taxonomic ambiguities and support effective fish management and conservation strategies. This study provides critical genetic data, advocates for molecular methods in biodiversity assessments, and underscores the ecological significance of accurately identifying native and invasive fish species in Indonesia and World.

Fat metabolism in toothed whales is different from other mammals. RT-qPCR is still a reliable technique for studying the relative expressions of various genes involved in metabolism. This study was done for Risso’s dolphin, a toothed whale and information produced here will be important for further transcriptomics studies focused on unrevealed marine mammal fat metabolism. In this study, we sought to identify a suitable reference gene with minimum resources. Seven candidate reference genes ZC3H10, FTL, LGALS1, RPL27A, GAPDH, FTH1 and DCN were initially tested for amplification efficiency using RT-qPCR by producing standard curves. Then, three nearly 100% efficient genes FTL, LGALS1 and GAPDH were selected for the gene stability analysis to determine one stable gene across eight different fat tissues, liver, and muscle of Risso’s dolphins based on four algorithms, provided in geNorm, NormFinder, BestKeeper and Delta Ct. Finally, a RefFinder comprehensive ranking was done based on stability values and the genes were ranked as: FTL>LGALS1>GAPDH. The FTL and LGHLS were identified as the most stable genes; however, GAPDH was third, a well-known housekeeping gene for mammals. Finally, we suggest using FTL as a reliable reference gene for functional genomics studies on toothed whales in the future.