International Journal of Aquaculture, 2025, Vol.15, No.3, 116-134 http://www.aquapublisher.com/index.php/ija 128 5.3 Conservation and aquaculture significance The results of this part of the Mekong River research are quite useful for protecting marble goby and improving aquaculture management. Let's talk about protection first. Although marble goby are widely distributed throughout the Mekong River basin and their numbers are quite stable, we still found obvious genetic differences. This shows that fish populations in different sections of the river actually have their own genetic characteristics and should be treated as different management units, not managed in a one-size-fits-all manner (He et al., 2022). For example, the group in the upper reaches of the Lancang River has developed a special haplotype because of its long geographical distance. If they are released downstream at will or mixed with the downstream population, genetic pollution may occur. This situation also poses a problem for the management of transnational waters. To protect the genetic diversity of these fish, it may require the cooperation of countries in the entire basin, and it cannot be done in one place alone. Secondly, more attention should be paid to possible hidden new species (such as the suspected new species population in Tonle Sap Lake). This cryptic species may have a specific ecological niche and a limited distribution range, and its population may be much smaller than the main population of marble goby, making it potentially threatened. If subsequent studies confirm that it is a new species, its threatened status should be assessed separately in the IUCN Red List and national conservation lists, and targeted conservation measures should be formulated. Even if it is not confirmed as a new species, this special lineage of Tonle Sap Lake should be protected, such as limiting the introduction of alien fish species to avoid competition and maintaining the natural hydrology of the lake to support its habitat needs. Let's talk about aquaculture. If you want to do a good job of breeding marble goby, you must first understand its population structure. Sometimes farms will introduce broodstock from different places. If you don't consider whether they come from different populations, you may mix up their genes. Studies have found that mating between closely related fish or populations with too simple genes will reduce their reproductive capacity and make them more susceptible to disease (Li et al., 2024). For example, although the marble goby in the upper and lower reaches of the Mekong River are not very different, they are still somewhat different in genes. They may have adapted to different living environments. Therefore, we can select marble goby in different regions based on these differences. For example, fish in the upper reaches may be more resistant to cold; fish in the lower reaches may live better in high temperature and low oxygen environments. This separate breeding can not only improve the survival rate, but also be more suitable for breeding conditions in various places. Another important point is to try not to let groups with too many differences breed together, so as to ensure that the germplasm is not destroyed. Finally, we want to say that this classification method that combines molecular data and traditional methods is not only useful for marble goby, but also helpful for the research and protection of other fish. Now that human activities are increasing, the survival pressure of freshwater fish is also increasing. Problems such as habitat destruction, overfishing, and invasive alien species are very common (Wantania et al., 2025). In this case, if you want to protect these fish, you must first figure out what each fish is and what genetic characteristics it has. If the classification is unclear, resources may be used in the wrong place. Sometimes "false species" are protected, and the groups that are really at risk are ignored. Therefore, we suggest that areas with abundant fish, such as the Mekong River, should use molecular methods for classification as soon as possible to discover more potential species differences and evaluate the conservation value of each type of fish. In this way, governments and conservation organizations can use resources on fish and groups that really need protection the most, and be scientific and efficient. 6 Challenges and Future Research Directions 6.1 Necessity of integrating nuclear genome data Although the mitochondrial genome plays a huge role in phylogeny and species identification, a single mitochondrial marker is sometimes not enough to deal with complex evolutionary problems. As mentioned above, mitochondrial DNA has the characteristics of maternal monophyletic inheritance and cannot reflect the paternal
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