A Bath Challenge Method with Tenacibaculum maritimum for Japanese Flounder Paralichthys olivaceus

A bath challenge method with Tenacibaculum maritimum was examined using juvenile Japanese flounder Paralichthys olivaceus. After immersed in the bacterial suspensions at different concentrations for 1 h, fish were maintained at 15 degrees C, 20 degrees C and 25 degrees C. At any temperatures, mortalities were 80-100% and 20-40% in fish challenged at 10(7.9) and 10(6.9) CFU/mL, respectively. No disease signs were observed in fish challenged at 10(5.9) CFU/mL. The affected fish exhibited mouth reddening and skin erosion, and T maritimum were re-isolated from the hemorrhagic skin lesions. The seed lot method used in the present study probably provided reproducible results with high mortality.