Abstract The toxicity of sniper – containing 2, 3-dichlorovinyl dimethyl phosphate (DDVP) on fingerlings and post fingerlings of Clarias gariepinus (African catfish) was investigated in a static bioassay for 96 hours. 100 pieces of fingerlings and 100 post fingerlings fishes weighing between 1.2g – 1.4g were obtained from a fish farm and transported to the Laboratory where they were kept for seven days to acclimate. A range finding test was conducted prior to the main test which had the following concentrations (0.0 – control, 0.10, 0.05, 0.025. and 0.0125mg/l) of Snipper in each static tank respectively. 10 Clarias fish were introduced into each static tank containing 20 litres of water about 30 minutes after treatment with the toxicant and observed for 96 hours. Data on fish mortality as well as the physico-chemical parameter (temperature, pH, dissolved Oxygen, nitrate) of water were recorded. The water quality parameters in the treatment tanks showed no significant difference with that of the control. Behavioral responses in the fishes include erratic and uncoordinated swimming which were observed to be more pronounced at higher concentration and time. Bleached body was the only external change observed and this was more pronounced in the fingerlings in higher concentration. The 96-hr LC50 for fingerling determined by probit analysis was 0.041mg/L. The result indicated that DDVP is highly toxic to fingerlings and post fingerlings of Clarias gariepinus. As such, caution should be exercised in the use and disposal of unused cans of sniper close to aquatic- systems.
Keywords 2,3-dichlorovinyl dimethyl phosphate (DDVP), Clarias gariepinus, probit analysis.