Efficacy of Febantel Against Gill Monogeneans of Amberjacks I: Laboratory Assessment for Effective Dose and Administration Period

Abstract

Three experimental trials were conducted to determine the effective dose and administration period of a pro-benzimidazole anthelmintic drug febantel (FBT) against two gill monogenean species on amberjacks; Zeuxapta japonica on Seriola dumerili and Heteraxine heterocerca on Seriola quinqueradiata. The mean Z. japonica intensities were checked at 3 days after given FBT-coated feeds at the doses of 1, 5, 10, or 20 mg/kg body weight (BW)/day (d) for 5 consecutive days (trial 1), and 10 mg/kg BW/d for 1, 3, or 5 days (trial 2). Based on the results of these trials, the efficacy of oral FBT treatment was assessed for H. heterocerca infections at the treatment regime of 10 mg/kg BW/d for 3 or 5 days (trial 3). Over 95% FBT efficacies were achieved for both monogenean species when the fish received the dose of 10 mg/kg/d or higher for 5 consecutive days. Amberjacks showed no apparent avoidance to the FBT-coated feed and no apparent signs of the drug toxicity were detected. Our results demonstrated that the in-feed FBT treatment at the dose of 10 mg/kg BW/d for 5 days is an effective, easy, and practical control measure against gill monogenean infections in aquaculture of Seriola fish.

Efficacy of Febantel against Gill Monogeneans of Amberjacks II: Field Trial Assessment

“…The high efficacy of FBT treatment, 99.9% to 100%, was achieved in all trials (Table 1). These results are in agreement with, or even better than, the laboratory trials in which the same drug treatment resulted in the efficacies ranged from 95.7% to 100% (Shirakashi et al, 2021a). Williams et al (2007) also achieved 100% efficacy of oral administration of PZQ against Z. seriolae on S. lalandi, but only via intubation.…”

“…The experimental feeds were prepared by the basic procedure described in Shirakashi et al (2021a). In brief, commercial FBT drug Marinebantel (25% FBT, Meiji Seika Pharma Co., Ltd.) was mixed with commercial dry pellet feeds: Hamachi Special size 4 (Marubeni Nisshin Feed Co., Ltd.) for trial 1, Marine size 6 (Maruha Nichiro Corp.) for trial 2, Hamachi Epd5K (Feed One Co., Ltd.) and Hamachi Kyusui EP5 (Marubeni Nisshin Feed Co., Ltd.) for trial 3, and Hamachi Special size 5 (Marubeni Nisshin Feed Co., Ltd.) for trial 4.…”

“…The experimental feeds equivalent to 2% body mass were given once a day to each group. Determination of gill fluke intensity for each gill sample followed the methods described previously (Shirakashi et al, 2021a). Briefly, flukes were dislodged from the ethanol-fixed gills by the "stirring method", collected on mesh, and counted under a stereomicroscope.…”

“…Briefly, flukes were dislodged from the ethanol-fixed gills by the "stirring method", collected on mesh, and counted under a stereomicroscope. Identification of the monogenean species based on the clamp arrangement was performed at the same time for the maximum of 10 haphazardly selected relatively large worms (mostly adults) per sample (Ogawa, 2011;Shirakashi et al, 2021a).…”

“…Our previous laboratory trials demonstrated that the oral administration of FBT via surface coated feed is also highly effective against two monogenean species infecting amberjacks, namely Heteraxine heterocerca and Zeuxapta japonica (Shirakashi et al, 2021a). The tank experiments resulted in efficacy rates of over 95%, up to 100% in some cases, in the fish that received FBTcoated feeds at the dose of 10 mg/kg BW/d for 5 consecutive days.…”