Effects of treatment with levamisole and glucans on mortality rates in Atlantic salmon (Salmo salar L.) suffering from amoebic gill disease

When levamisole was added to freshwater baths, used to treat Atlantic salmon for amoebic gill disease (AGD), there was a significant decrease in subsequent mortality of the fish. This was particularly the case in fish experiencing their first exposure to AGD. There were no significant differences in responses to 1.25, 2.5 and 5.0 mg/L levamisole. It is proposed that this response is related to enhancement of the non-specific immune system. Oral supplementation with levamisole or glucans did not prevent subsequent moralities when Atlantic salmon, naive to AGD were subsequently exposed to this disease.