10.22376/ijpbs.2019.10.1.p1-12 Volume 12 Issue 3 2021 (July-September) The pesticides are used in agriculture and public health against the control of disease vectors, as protection of material, incorporation in paints, timber, glues, plastic sheeting etc. Pesticides are also used to prevent insects in industry, for the control of hazardous vegetation in forest, airport, factory sites and fumigation of ships and warehouses, in the household and garden spray and control of ectoparasites like fleas, lice, ticks and lessThan i greaterThan lessThan /i greaterThan mites in pet animals and as an application to clothing and skin. Pesticides are of various categories like organophosphates, organochlorines, carbamates and pyrethroids. Various less known categories are also present like organometallic compounds can be used as pest killers. In ancient times nicotine, arsenic was also used as pest killer solutions. Fenitrothion is a pyrethroid having alpha cyano group and not easily biodegradable, hence creating bioaccumulation in ecosystems. These pesticides adversely affect the aquatic system, especially fishes. The aim of present study is to determine harmful effects of conventional pesticides used in many parts of Uttar Pradesh on non-target species for which lessThan i greaterThan Catla catla lessThan /i greaterThan has been selected and the effect was observed on neurotransmitters from brain under stress of fenitrothion. It is very common in western UP. This will bio accumulate in fish body and when these fishes are consumed by humans, will create many types of toxicity. The harmful effect of fenitrothion is mainly due to its cyano group which interacts with neurotransmitters. Hence it can be concluded that this pesticide may not be used or replaced with some other organic pesticide to conserve biodiversity as well as to prevent human health. This study is aimed for both aquatic fauna and indirectly linked to long term effects on human health. Sarika Tomar, Sushil Kumar, A.K.S. Chauhan and H.N. Sharma Fenitrothion, Catla catla, Neurotransmitter, Brain, Aquatic ecosystem, Non target species 50-55