Effect of Endosulphan and Dimethoate Pesticides on Haematological Parameters of Fresh Water Fish Channa punctatus
Fish hematology is one of the most recent branches of physiology to assess the status of general health. Blood is the transport medium, a defense system, and an acid/base buffer system. Circulating blood is the common denominator of health and illness and alteration in its chemical or cellular illness and composition can indicate hematological and nonhematological diseases. Erythrocytes occupy the largest fraction of the formed elements of the blood. For hematological observations of the fish Channa punctatus, blood from control and experimental fish was drawn directly from the ventricles after exposing the heart, with the help of a syringe fitted with 20 gauze needle. The blood without anti-coagulant was directly used for the total erythrocyte count (TEC), total leucocytes count (TLC) and smear preparation. The number of erythrocytes per cubic millimetre of blood was calculated with the help of a hemocytometer using a Neubaur’s counting chamber. The method given by Dacie and Lewis was followed to count the number of leucocytes. Blood was drawn up to 0.5 mark of the WBC pipette and diluted up to 11 mark with Turk’s fluid and the number of WBC in corner most four squares, whose area is 1 sq. mm were counted. For the preparation of blood smear standard glass slides washed in 100% ethanol were used. Blood film was made immediately after the blood was drawn from the fish. From each fish, four blood smears were prepared using Leishman’s, Gimsa, Wright’s and Field stains. The morphology and staining property of all types of blood corpuscles were studied. For differential leucocytes counts, at least 100 leucocytes were observed and counted for each blood smear at a time, and differentiated into various types: monocytes, lymphocytes, neutrophils, eosinophils and basophils.
Differential leucocytes count also was altered in fish exposed to endosulfan and dimethoate. Basophils are quite scanty in normal circulating blood. Basophils decreased in all the exposures, increase in eosinophils on exposure to dimethoate and decrease on exposure endosulfan for 96 hr was observed in the present findings. In the present study increase in neutrophils number was recorded upto 72.0% in fish exposed to endosulfan. In the present study both the pesticides decreased the number of basophils, eosinophils, monocytes, lymphocytes, neutrophils and RBC in Channa punctatus after 96 hr, except in few observations. Number of eosinophils, monocytes and lymphocytes in endosulfan exposures; only eosinophils and lymphocytes count in dimethoate exposure was increased after acute exposure.