Effect of sodium hypochlorite on zebrafish swimming behavior estimated by fractal dimension analysis

The behavioral responses of zebrafish (Danio rerio) to sublethal concentrations of sodium hypochlorite (NaClO)-based household bleach were quantified in order to index toxicity of the solution. The swimming behavior of zebrafish was captured using nonplanar 3D stereocameras in combination with 3D coordinate computation with perspective correction (3DCCPC) to compute for actual 3D coordinates. Swimming trajectory and velocity were quantified by fractal dimension analysis. The results showed that, under incremental concentrations of NaClO-based aqueous solutions with the maximum of 0.005% v/v, the fractal dimension of swimming velocity trended to increase with the concentration. The fractal dimension of swimming trajectories trended to increase with pH. Hence, the results have proven that the system is a useful tool to indicate behavioral changes, which may be implemented in biomonitoring systems for acute toxicity bioassay.