Enhancement of immune responses in Indian carp, Catlacatla, following administration of Levamisole by immersion

Abstract

Effects of short term administration of levamisole by immersion on immune responses of the cultured food fish, Catla catla were investigated. Sub-adults of C. catla were given two hr bath in 1.25 or 2.5 mg/L levamisole solutions and the immune responses were assessed on 14, 21, 28, 42 and 56 days after the treatment in comparison to the controls. Results revealed that leucocrit levels, total leucocyte counts, abundance of leucocytes, total phagocytic activity, phagocytic index, myeloperoxidase activity and oxygen radical production by phagocytes were increased significantly in levamisole treated fish in comparison to the controls. No significant differences in the degree of immuno-stimulation were seen between the fish groups exposed to the two concentrations of levamisole tested. For both exposure levels, most of the parameters tested were greatly elevated on 42 days post exposure to levamisole. Challenge experiments showed that levamisole treated fingerlings of C. catla co-habitated with gold fish which had been infected with Ichthyophthirius and Dactylogyrus exhibited lower infestation levels and mortalities in comparison to the control fish. Levamisole treated C. catla which had been challenged with Aeromonas hydrophila displayed comparatively less mortalities compared to the controls. The results support the potential use of levamisole as an immunostimulant in culturing this fish.