Lumpfish (Cyclopterus lumpus) has become one of the most utilized cleaner fish for Atlantic salmon (Salmo salar) aquaculture in the north Atlantic region. Lumpfish in aquaculture sea-cages are known to prey upon ectoparasitic sea lice (e.g., Lepeophtheirus salmonis), which is a major threat to salmon farming around the world. Lumpfish perform well in cold environments, and are routinely commercially utilized as a form of pest biocontrol, since 2013 in Norway and 2017 in Atlantic Canada. Although healthy populations of lumpfish could theoretically be utilized over two salmon production cycles, biosecurity concerns and maintaining the long-term health of domesticated lumpfish remains challenging. Bacterial infectious diseases are the most frequent health issues of lumpfish impacting their performance and extended utilization. We have developed several bacterial infectious disease models in lumpfish for vaccines and bacterial pathogenesis studies. Here, advances in lumpfish immunity and infection of Vibrio anguillarum, Aeromonas salmonicida, Pseudomonas nov., sp. J380, Moritella viscosa, Renibacterium salmoninarum, and Piscirickettsia salmonis are examined and discussed. Bacterial infection and immune transcriptomics studies indicated that marine Gram-negative pathogens generally cause a more acute infection than Gram-positives. Among the tested pathogens in lumpfish, A. salmonicida and V. anguillarum are the most virulent. M. viscosa caused a distinctive gill inflammation and acute death. Pseudomonas nov., sp. J380 is an endemic pathogen that could infect lumpfish. P. salmonis is fully lethal in lumpfish, independent of the infectious dose, and causes slow morbidity and mortality rates with distinctive clinical signs. R. salmoninarum causes a chronic type of infection with characteristic clinical signs of bacterial kidney disease. These infectious models are a contribution to marine teleost immunity knowledge and vaccine development, towards a more efficient utilization of lumpfish in aquaculture sea lice biocontrol.