抄録
Microflora in the surface water of three tanks rearing larval Japanese flounder (Paralichthys olivaceus) was investigated. Bacterial densities ranged from 6.9×104 to 1.2×106 CFU/ml, and Flavobacterium-Cytophaga group and Pseudomonas-Alteromonas group accounted for 15-70% and 25-85% of viable bacteria, respectively. Members of genus Vibrio were detected in all water samples at densities of 9.0×100 to 1.0×104 CFU/ml, and Listonella anguillarum and V.ordalli were detected in tanks 2 and 3, and tanks 1 and 3, respectively, even when no symptom of vibriosis appeared. These results strongly suggest that the vibriosis causative agents such as L. anguillarum and V.ordalli are inhabitants at low densities in the tank water of larval Japanese flounder cultivated by both the conventional and ‘hottoke-shiiku’methods.
