Vaccine preparation and method for preventing iridoviral infection in fish containing deactivated iridovirus as an antigen and having uniform quality

Provided is a more effective means for controlling iridovirus infection of fish against fish species of the genus Ishidai. is the solution of the present invention is to provide a vaccine preparation for fish iridovirus infection, which contains deactivated iridovirus as an antigen and is administered at least 107.0 TCID50 at a time. By administering the deactivated iridovirus as an antigen at least 10 TCID50 at a time, iridovirus infections such as red sea bream illnesses, which have been previously considered to be less effective in vaccines for the genus Ishidai, can be effectively prevented. The concentration of the iridovirus in the vaccine preparation can be increased to 10 TCID50 or higher by containing a concentrated solution of the culture supernatant for proliferating the cultured cells of the iridovirus, or the culture supernatant and the virus-infected cultured cells, etc.