Evaluate effect of Levamisole on immune system and resistance against density stress in rainbow trout (Oncorhynchus mykiss)

Because of existing different stresses in fish farms, there is necessary to corroborate immune system of fishes against stresses. In the present study effects of Levamisole on immune responses of rainbow trout were evaluated. For this purpose 1000 pieces fish (average weight of 150 g) were obtained from a local fish farm of Urmia and were divided in 5 test groups (33 kg/m3 density) and were fed on diet supplemented with Levamisole at 0, 100, 250, 500 and 1000 mg per kg of diet for a period of 45 days. Then the fishes of all groups were fed on commercial diet without Levamisole and were exposed density stress by 2-3 folds for the following 15 days. Blood samples were collected from all groups on days 0, 15, 30, 45 and 60 to evaluate the serum total immunoglobulin, complement system activity and lysozyme activity. The results showed that, at the end of trial (day 60) Significantly (P