摘要：The present study was undertaken to evaluate the toxic effects of butachlor, a widely used herbicide on Indian major carp C. mrigala in terms of micronucleus assay and growth performance. Fish were exposed to 1.0 ppm, a sublethal concentration of butachlor and micronucleus assay was carried out after 24, 48, 72 and 96 h. Peripheral blood was collected and smear was prepared using Giemsa stain to analyse micronuclei. A positive control was also maintained. Growth performance of fish was studied for a period of 60 days during which fish were fed on a diet containing 40% protein. Growth parameters were calculated and carcass composition was analysed according to standard procedures. Frequencies of micronuclei reveal a significant (p<0.05) time dependent response, being higher at 48 h of exposure. Broken Egg (BE) and multiple micronuclei appeared after 72 and 96 h, respectively showing the genotoxic effect of the chemical. Fish growth studies also depicted a growth repressing effect due to butachlor. On exposure to 60 days a significant (p<0.05) decrease in fish growth was observed in terms of live weight gain, length gain and growth % gain in b.wt. Significantly (p<0.05) low accumulation of carcass protein and low gross energy in the butachlor exposed fishes were observed. Muscle glycogen levels were also significantly (p<0.05) low in the group of fishes exposed to butachlor indicating that this herbicide persists in the aquatic system for a long period of time. These results together with those related to mutagenicity demonstrate the risk that butachlor possess.
