The bitterling (Cyprinidae, Acheilongnathinae) is a temperate freshwater fish with a unique spawning symbiosis with host mussels. Female bitterlings use their extended ovipositors to lay eggs on the gills of mussels through the mussel's exhalant siphon. In the present study, in April of 2020, we investigated spawning frequencies and patterns of three bitterling fish species in host mussel species in the Nakdong River basin (Hoecheon). During field surveys, a total of four bitterling and three mussel species were found. We observed bitterling's spawning eggs/larvae in the three mussel species: Anodonta arcaeformis (proportion spawned: 45.5%), Corbicula fluminea (12.1%), and Nodularia douglasiae (45.2%). The number of bitterlings’ eggs/larvae per mussel ranged from 1 to 58. Using our developed genetic markers, we identified the eggs/ larvae of each bitterling species in each mussel species (except for A. macropterus): A. arcaeformis (spawned by Acheilognathus yamatsutae), C. fluminea (A. yamatsutae and Tanakia latimarginata), and N. douglasiae (A. yamatsutae, Rhodeus uyekii, and T. latimarginata). Approximately 57.6% of N. douglasiae mussel individuals had eggs/ larvae of more than one bitterling species, suggesting that interspecific competition for occupying spawning grounds is intense. This is the first report on bitterling’s spawning events in the Asian clam C. fluminea from Korea; however, it should be ascertained whether bitterling’s embryo undergoes successful development inside the small mussel and leaves as a free-swimming juvenile. In addition, the importance of its conservation as a new host mussel species for bitterling fishes needs to be studied further.

1. 서 론
2. 재료 및 방법
    2.1. 연구대상 지역
    2.2. 조사 및 분석 방법
3. 결 과
    3.1. 재첩 내 납자루아과 산란 관찰 및 숙주조개종 특이성, 산란율 및 종간경쟁
    3.2. 납자루아과 어류 3종간 산란양 및 아가미 내산란위치 차이
    3.3. 민물조개 크기에 따른 산란선호도
4. 고 찰
    4.1. 재첩 내 납자루아과 산란 관찰 및 숙주조개종 특이성, 산란율 및 종간경쟁
    4.2. 납자루아과 어류 3종간 산란양 및 아가미 내산란위치 차이
    4.3. 민물조개 크기에 따른 산란선호도
적 요
사 사

• 서진규(상지대학교 생명과학과 분자생태및진화학실험실) | Jin Kyu Seo (Molecular Ecology and Evolution Laboratory, Department of Biological Science, Sangji University, Wonju 26339, Republic of Korea)
• 최희규(상지대학교 생명과학과 분자생태및진화학실험실) | Hee-kyu Choi (Molecular Ecology and Evolution Laboratory, Department of Biological Science, Sangji University, Wonju 26339, Republic of Korea)
• 이혁제(상지대학교 생명과학과 분자생태및진화학실험실) | Hyuk Je Lee (Molecular Ecology and Evolution Laboratory, Department of Biological Science, Sangji University, Wonju 26339, Republic of Korea) Corresponding author