Effective control of Neobenedenia girellae infestation by an optimized oral protocol in greater amberjack juveniles (Seriola dumerili)

Infestations by Neobenedenia girellae constitute significant challenges to the culture of greater amberjack (Seriola dumerili), a promising species for aquaculture diversification. The impact of these infestations is further amplified by global ocean warming, underscoring the urgent need for effective prevention and control measures. This study assessed the efficacy of different praziquantel (PZQ) treatments on growth performance, muscle kinetic profiles (Experiment 1), and their ability to control N. girellae infestations in S. dumerili juveniles reared in an open seawater system (Experiment 2). In Experiment 1, six treatments were tested: T1 (Control), T2-PZQ 2.25 %-1 (450 mg PZQ/kg live weight, single dose), T3-PZQ 1.125 %-2 (225 mg PZQ/kg live weight, 2 days), T4-PZQ 0.75 %-3 (150 mg PZQ/kg live weight, 3 days), T5-PZQ 0.75 %-2 (150 mg PZQ/kg live weight, 2 days), and T6-PZQ 0.75 %-1 (150 mg PZQ/kg live weight, single dose). In Experiment 2, protocols T1–T4 were evaluated. Results indicated that growth performance was unaffected by PZQ treatments, and muscle PZQ concentrations returned to baseline within 48 h post-administration. Protocols T3–1.125 %-2 and T4–0.75 %-3 exhibited the highest efficacy against N. girellae adults, achieving 91 % and 99.8 % parasite reduction, respectively. The protocol involving 150 mg PZQ/kg administered over three consecutive days proved to be the most effective for managing N. girellae infestations, without compromising fish growth and with minimal muscle residue persistence.