Lumpfish (Cyclopterus lumpus L.), also known as lumpsucker, are now farmed and used as cleaner fish to remove sea lice from farmed Atlantic salmon in Europe and Canada (Powell et al., 2018;Treasurer, 2018;Haugland et al., 2020). In Norway, the number of farmed lumpfish has increased rapidly in recent years and 34 million lumpfish were deployed in 2020 (http://www.fiske ridir.no). High mortality among lumpfish has been reported, most caused by bacterial infections with atypical Aeromonas salmonicida, Vibrio spp., Pasteurella sp.