Amoebic gill disease (AGD) is a major disease threat that has had high economic impact in the Scottish Atlantic salmon aquaculture industry, having emerged as an escalating problem in recent years. The aetiological agent is the amoeba Paramoeba perurans. Currently control measures are restricted to treating sea cages with fresh water or hydrogen peroxide. This approach is expensive and logistically difficult and can have detrimental impacts on fish health and welfare. This project is funded directly by Ridgway Biologicals Ltd (RWB) to continue the work performed on project 944885. The aim is to conduct a second AGD vaccine trial to test the efficacy of a recently developed autogenous vaccines against AGD in Atlantic salmon.