Bacteriophages are ubiquitous in aquatic environments and are known to have great influence on the bacterial composition of these. This is also true for bacteriophages infecting bacteria with relevance to fish farming. Lysogenic bacteriophages are often carriers of virulence genes in pathogenic bacteria, and lytic bacteriophages have been linked to the natural clearance of bacteria at the end of disease outbreaks. Excessive use of antibiotics and the increasing emergence of resistant bacteria have called for novel approaches to treatment of bacterial disease in aquaculture. One such alternative is the therapeutic use of bacteriophages. ACD Pharmaceuticals has been working with phages for therapeutic application in aquaculture since 2011. Here we present results, experiences and views on phage therapy applied in fish farming.