Median lethal dose (LD50) determination Groups of 10 fish with an average
weight of 10 g were tested for pathogenicity against S. agalactiae. Each group was kept
in a 45 L aquarium at 25 °C throughout the experiment. From an initial bacterial
concentration of 6.0×108 CFU/mL, 10-fold serial dilutions were prepared. Fifty microliters
of each dilution was injected intraperitoneally into each fish. The control group
was intraperitoneally injected with 50 μl of physiological saline instead of the bacterial
suspension.