Efficacy of Bath-Administered Flumequine and Oxolinic Acid in the Treatment of Vibriosis in Small Atlantic Halibut

In this investigation, the efficacies of bath-administered flumequine and oxolinic acid in the treatment of vibriosis in small Atlantic halibut Hippoglossus hippoglossus were examined. In a laboratory challenge experiment, halibut (3–5 g) were exposed to Vibrio anguillarum strain (isolate HI 11347) at a concentration of 4.0 × 108 bacteria/mL for 30 min. Bath treatments, initiated 24 h after challenge at a concentration of 150 mg of flumequine or 200 mg of oxolinic acid per liter for 72 h, significantly (P < 0.05) lowered the V. anguillarum-specific mortality in the drug-treated groups compared with the untreated control group. In another trial in which the bacterial challenge was reduced to 3.2 × 108 bacteria/mL (80% of initial dose) and the bath treatment with flumequine (150 mg/mL) was begun on days 2, 3, or 5 postchallenge, the cumulative mortality was significantly (P < 0.05) different from the control group only when treatment was initiated on day 2 postchallenge. Bacterial examination of kidneys from dead and surviving fish indicated the pathogen was quickly and effectively eliminated by the antibacterials.