Production of salmonid amoebic gill disease by exposure to Paramoeba sp. harvested from the gills of infected fish

Atlantic salmon, Salmo salar L., were exposed to different concentrations of Paramoeba sp. The lowest concentration which induced amoebic gill disease (AGD) was 230 Paramoeba sp. L-1 and the severity of infection increased with increasing concentration. The concentration of Paramoeba sp. positively correlated with the number of gill lesions (R2 > 0.7). This study provides evidence that Paramoeba sp. is the causative agent of AGD and describes an experimental model that enables the severity of the induced disease to be controlled.