Short-term exposure to quinalphos induced biochemical and haematological changes in freshwater fish, Oreochromis mossambicus

The toxic impact of quinalphos, an organothiophosphate, on the biochemical as well as haematological parameters was studied in the adult freshwater fish, Oreochromis mossambicus. In the present study, 0.5µl/ L quinalphos was chosen to represent sublethal concentration for 48 and 96 hours as short-term exposure and respective control animals were maintained. Quinalphos induced toxic stress to the exposed fishes, which is obvious by the reduction in the oxygen consumption of the fishes at the time of exposure and this could be due to shrinkage of the respiratory epithelium or possibly due to mucus accumulation on gills. Decrease in the haemoglobin content was observed and this may be due to either an increase in the rate at which the haemoglobin is destroyed or decreased rate of haemopoietic potential of the fish. In the present study, the significant increase in WBC count indicates hypersensitivity of leucocytes to quinalphos and these changes may be due to immunological reactions to produce antibodies to cope up with the stress. Decrease in the level of RBC count indicated decrease in erythropoietic activity or severe anemic state. Reduction in the plasma and tissue protein of quinalphos exposed fishes may be due to its utilization to mitigate the energy demand when the fishes are under stress. Increase of plasma glucose and the total glucose content in tissues like liver, muscle and gill might have resulted from gluconeogenesis to provide energy for the increased metabolic demands imposed by quinalphos stress. Thus the biochemical and hematological alterations due to acute short-term exposure to quinalphos were due to the toxic stress of the toxicant.