International Journal of Molecular Ecology and Conservation, 2025, Vol.15, No.4, 153-162 http://ecoevopublisher.com/index.php/ijmec 15 4 In view of the possible ecological risks brought by the invasion of black fish, the management departments of various countries have begun to pay attention to its spread dynamics and source tracing. However, there may be differences in the genetic background and invasion mechanism of black fish populations in different regions, and the understanding of their global diffusion patterns is still insufficient (Bock et al., 2016; Resh et al., 2021). The development of molecular ecological methods has provided new tools for revealing the transmission paths of invasive species and their adaptive evolution. For example, population single nucleotide polymorphism (SNP) data obtained by high-throughput sequencing can be used to trace the origin of invasive populations and monitor changes in genetic diversity (Cristescu, 2016; Resh et al., 2021). This study will summarize the research progress on the genetic differentiation and invasion spread of black fish species in recent years, with a focus on the species diversity of the main black fish species and the geographical distribution patterns of their native habitats and invasion sites. Reveal the genetic structure of black fish populations and the genetic differentiation between native and invasive populations by using molecular markers; The ecological and genetic mechanisms of the invasive spread of black fish Typical regional case analysis of the spread patterns and genetic characteristics of black fish, as well as the challenges and future research directions faced by black fish invasion management. This study aims to deepen the understanding of the global invasive biology of black fish and provide a scientific basis for formulating effective prevention, control and management strategies. 2 The Species Diversity and Distribution Overview of the Genus Channa 2.1 Introduction to the main species of the genus Channa The genus Channa contains approximately 30 to 40 valid species in taxonomy and is widely distributed in tropical and temperate regions of Asia. It is an important carnivorous fish group in the inland waters of Asia. Among them, representative species include: Northern black fish (Channa argus), which is native to Northeast China, the Korean Peninsula and the Russian Far East (Figure 1) (Liu et al., 2024); The striped black fish (Channa striata) is widely found in countries in South and Southeast Asia. The red-scaled black fish (Channa micropeltes), also known as the giant black fish, is distributed in places such as the Malay Peninsula, Sumatra and Borneo in Southeast Asia. And other species such as the South Asian eye-spotted black fish (Channa marulius), Fujian black fish (Channa maculata), etc. (Conte-Grand et al., 2017; Harrington et al., 2022). Different black fish species have certain differences in ecological habits and life history strategies, which may affect their invasive ability. For example, the northern black fish ADAPTS to the temperate climate, can tolerate lower water temperatures, and can overwinter and reproduce in areas with lower annual average temperatures (Resh et al., 2021); The striped black fish prefers shallow water environments in tropical and subtropical regions and has the ability to sleep in the mud during the dry season and survive in harsh conditions. In terms of reproductive strategies, black fish generally belong to the multiple spawning type, with a high spawning frequency and a large single spawning quantity each year. The fertilized eggs have oil ball buoyancy and gather into clusters to float on the water surface. The parent fish will carry out the behavior of protecting the young for several weeks (Orrell and Weigt, 2005; Li et al., 2016). These characteristics enable black fish to reproduce efficiently and maintain population growth even in the absence of natural enemies after being introduced into new waters (Harrington et al., 2022). 2.2 Distribution pattern of origin and invasion areas The species of black fish are mainly native to East Asia, South Asia and Southeast Asia, including most parts of China, the Indian subcontinent and the countries of the Indochinese Peninsula, as well as the Indonesian archipelago, etc. (Conte-Grand et al., 2017). Within the original habitat, black fish populations in different geographical regions often form genetic differentiation due to historical geographical isolation. For example, the striped black fish has differentiated into several local populations or lineages in Southeast Asia (Duong et al., 2019; Robert et al., 2019). In recent decades, due to human activities, black fish have been introduced to many countries outside Asia, with the most notable invasion in North America. Since the end of the 20th century, invasive black fish have been
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