author(s)
Sivakumar P., Kanagappan M. and Sam Manohar Das S.

abstract
When exposed to different concentration of a toxicant, the physiology and the whole system of the fish found to be disturbed and affected. In the present investigation, toxicity evaluation and behavioral changes in the fish Danio rerio (Zebrafish) were studied. The freshwater fish Danio rerio was exposed to tannery effluent in static test for the LC50 values for 12 to 96 hrs and the LC50 values were 54.314 for 12 hours, 52.940 for 24hrs, 51.967 for 36 hrs, 51.461 for 48 hrs, 50.878 for 60 hrs, 50.171 for 72 hrs, 49.221 for 84 hrs and 48.448 for 96 hrs respectively. The LC50 values found to be decreased constantly with increasing period of exposure. This indicated that low concentration of a toxicant is also toxic to the fish Danio rerio. Alterations in behavioural patterns were also well marked during the period of the experiment.