neem leaf juice as bio-safe anaesthetic against two live fish, anabas testudineus and channa punctata

activity of fresh neem leaf juice to immobilize, anaesthetize and fatal effect were studied against two live fish species, anabas testudineus and channa punctatus. the concentrations, 5, 10, 15 and 20% of neem leaf juice affected both the species, but a.  testudineus was found to be comparatively more susceptible to the treatment  than c.  punctatus . the time required to immobilize were 4 to > 6 hours for a. testudineus and 7 to 9 hours for c.  punctatus ; to anaesthetize were 6 to > 12 hours and 8 to 10.15 hours for a. testudineus and c.  punctatus respectively; and death occurred 7 to > 13 hours in a. testudineus and 9 to 10.45 hours in c.   punctatus after treatment depending on the concentrations. the toxic effects were positively co-related with the concentrations and negatively co-related with the total weight of the fish, though the values of the coefficient of the correlations (r) were low. at the anaesthetic stage, the colour of skin, gills and eye were changed, the fishes showed irritated movement first ( a. testudineus ) and then became sluggish (both species), and instead of the normal fishy smell the fishes gave neem leaf like smell.