DOI: 10.36347/sajb.2014.v02i07.002

Pages: 404-409

Fish and other organisms are affected by pesticides which pollute the natural water through agricultural runoff and various other means. The aim of this study was to determine and compare the acute toxicities of three different categories of pesticides viz organochlorine (endosulfan), organophosphate (chlorpyrifos) and synthetic pyrethroid (permethrin) which are commonly used in agricultural practices. Adult male and female zebrafish were randomly selected and exposed to these three pesticides. The toxicity tests were performed separately for each pesticide. The mortality rate of zebrafish was monitored under laboratory conditions for the time period of 96-h. Data obtained from the toxicity tests were evaluated using the Probit Analysis Statistical method. The toxicity tests gave the 96-h LC50 values as 0.10, 0.16 and 0.13µg/l for endosulfan, chlorpyrifos and permethrin respectively. The LC50 values revealed that all the three pesticides were highly toxic and the zebrafish showed highest sensitivity towards endosulfan followed by permethrin and chlorpyrifos. Further, the fish exhibited respiratory distress (such as gasping in air), loss of balance and erratic swimming prior to death. It was also found that the toxicity of these pesticides were time as well as concentration dependent. It could be concluded that these pesticides are extremely toxic and should be used very carefully. Zebrafish can be used as bioindicator to assess the pesticidal pollution in aquatic environment.