Effect of povidone-iodine (PVI) treatment on the viability of Renibacterium salmoninarum, the causative agent of bacterial kidney disease (BKD) was investigated in vitro. ​A novel dilution plating for Tok46 strain revealed that WOAH's shortest recommended treatment for hardened eggs (100 ppm available iodine for 10 min) achieved 4.6-log reduction in the colony-forming units. ​Treatment with higher concentrations of available iodine achieved further reduction. ​The effectiveness at 100 ppm was validated across two additional strains by turbidity measurements. ​The disinfection using the conventional procedures likely reduces transmission risk of BKD while those with higher concentration of PVI will be more effective.

Numerous blackish-brown foreign bodies of varying sizes were found in the abdominal cavity of a wild surge grouper Epinephelus socialis caught by angling in the Ogasawara Islands, Tokyo, Japan, in June 2023. ​These contained ellipsoidal to pyriform microsporidian spores, with a mean length of 5.9 μm and a width of 2.7 μm. ​Sequencing of the small subunit rRNA gene of the spores revealed a close phylogenetic relationship with Glugea microsporidia, including Glugea epinephelusis, G. nagelia, G. arabica, G. serranus, and G. eda. ​This suggests that the microsporidia belong to the genus Glugea and that the foreign bodies within the surge grouper's abdominal cavity were Glugea cysts. ​This study represents the first report of Glugea sp. parasitizing surge grouper.