2024 年 59 巻 1 号 p. 25-28
Mycobacteriosis caused by several mycobacterial species is often found in indoor pools where yearling koi carp are reared during the winter season in Niigata, Japan. In this study, we isolated several mycobacterial species from juvenile fish cultured in earthen ponds in August and October 2019. Further, antibody titers against two major causative species (Mycobacterium paragordonae and Mycolicibacterium sp. WS-type) rose not only in infected fish but in some individuals from which no bacterium was isolated. These data suggest that juvenile carp are infected in earthen ponds by autumn, the disease progresses, and subsequently the fish mortality occurs from winter to the next spring.
