Toxicity of phosphamidon on the gills of a freshwater fish, Anabas testudineus

An array of wide spectrum chemicals and their combinations are now being used as insecticides, fungicides,herbicides, nematicides, rodenticides and molluscicides. Kuttanad, the rice bowl of Kerala, India (Altitude– sea level; Latitude – 9.9 N and Longitude – 76.2 E) is a region where there is over application of pesticideduring the punja cultivation periods. Phosphamidon, Monocrotophos, Henosan and Thymet are the majorcomponents of the pesticides being used in Kuttanad. The exposure of fish to pesticides is likely to inducea number of lesions in body organs like gills, liver and kidney. The gills are the most important and sensitiveorgans of a fish body, which first experience the hazards of, polluted ambient water. As the fish gills areexposed to pesticides, a wide variety of structural changes in fish gills have been reported. They arehypertrophy, hyperplasia, oedematous separation of respiratory epithelium, telengiectasis, stasis,hemorrhage, necrosis, etc. The study shows that the pathological changes are gradually increasing fromthe lowest concentration to the highest concentration. The present study is aimed at assessing the extent ofPhosphamidon induced histological changes in the gills of Anabas testudineus, a fresh water food fish widelyinhabiting the paddy fields of Kuttanad, Kerala, India, and to arrive at a Maximum Allowable ToxicantConcentration (MATC) and an Application Factor (AF) based on the histopathology. This end point givesan ‘early warning’ of the damage caused in the fish at the histological level before their mortality. Hencepreventive measures can be taken to protect the fishery resources. Based on the index value, the MATC is3.1623 ppm and the Application Factor (AF)is 0.0804.