Antibacterial treatment of lumpfish (Cyclopterus lumpus) experimentally challenged with Vibrio anguillarum, atypical Aeromonas salmonicida and Pasteurella atlantica

Lumpfish is a novel farmed species used as cleaner fish for the removal of lice from farmed salmon. As often with new, farmed species, there are challenges with bacterial infections. The frequency of prescription of antibiotic agents to lumpfish is increasing, despite the lack of knowledge about appropriate doses, duration of treatment and application protocols for the various antibacterial agents. In the current study, we have tested the effect of medicated feed with florfenicol (FFC), oxolinic acid (OA) and flumequine (FLU) on lumpfish experimentally challenged with Vibrio anguillarum, atypical Aeromonas salmonicida and Pasteurella atlantica. We found that all three antibacterial agents efficiently treated lumpfish with vibriosis using 10 and 20 mg kg(-1) day(-1) of FFC, 25 mg kg(-1) day(-1) of OA and 25 mg kg(-1) day(-1) FLU, whereas only FFC (20 mg kg(-1) day(-1)) had good effect on lumpfish with pasteurellosis. None of the antibacterial agents were efficient to treat lumpfish with atypical furunculosis. FFC 20 mg kg(-1) day(-1) showed promising results in the beginning of the experiment, but the mortality increased rapidly 14 days post-medication. Efficient treatment is important for the welfare of lumpfish and for reducing the risk of development of antibiotic-resistant bacteria. To our knowledge, this is the first study to establish protocols for antibacterial treatment of lumpfish.