Cryptic biodiversity of freshwater fish species in Bangladesh

PLOS One | https://doi.org/10.1371/journal.pone.0318982 April 28, 2025 15 / 18 PLOS One Cryptic biodiversity of freshwater fish as well. Furthermore, the specimens we studied are poorly preserved, with some having lost their scales and/or fins. The key morphological features of each proposed cryptic species need further check and investigation with the type locality specimen whether our speculated cryptic species have any diagnosable character or not. Because, in this study we just focused cryptic species based on molecular data along with limited morphological feature which does not give any guarantee that they are each a new species. Additionally, digital photos must be captured to accurately verify the identity. In this study, we identified several COI sequences and connected them to previously identified species, but they have recommended that the most significant aspect of the DNA barcoding is that the end users can access it and can alter taxonomies to help with identifica- tion, nomenclature, species delimitation, introgression, and multiple mitochondrial lineages [14]. However, it appears that this was only the beginning of the barcoding effort. As a result, this study is an extra effort to produce more DNA barcode data and facilitate specimen identification. A major portion of Bangladesh’s small indigenous species is a primary source of protein. Together with the recent developed deep learning-based techniques [38] and molecular-morpholgy based species/genus identification [39] our DNA barcode library can

assist the accurate species identification and contribute to their proper management for con- servation. To prevent a potential wave of extinctions, we must quickly curtail anthropological activities that are detrimental to freshwater fish populations [40]. Immediate habitat resto- ration and species-specific conservation efforts are essential to save our valuable fish species and fisheries biodiversity in Bangladesh. Conclusion Annotated species lists are essential for creating appropriate conservation policies. Our findings of seven cryptic species (Table 2, Fig 5) provide additional information regarding the freshwater species check list in Bangladesh. To figure out the taxonomic status of the Fig 5. Seven possible cryptic species found in this study. (A) Ailia sp. (Ailiidae), (B) Awaous sp. (Gobiidae), (C) Lepidocephalichthys sp. (Cobitidae), (D) Ophich- thys sp.(Synbranchidae), (E) Erethistes sp. (Sisoridae), (F) Schistura sp.(Nemacheilidae) and (G) Cynoglossus sp. (Cynoglossidae). Not in scale. https://doi.org/10.1371/journal.pone.0318982.g005