Adverse Effect of Insecticides on Various Aspects of Fish’s Biology and Physiology

Abstract

Today, water quality management faces greater problems than at any time in its history. In addition to natural pollutants, varied contaminants exist in surface waters including multiple chemical compounds and different products of industrial and agricultural revolution. The insecticides constitute one group of these pollutants, both synthetic and natural, which contribute to the environmental problems. At present, it seems that the problem is more conspicuous in developing countries, where lately there has been an increase in the use of insecticides as a means of increasing agricultural productivity, without much concern to the consequences of indiscriminate application. There are many pathways by which insecticides leave their sites of application and distribute throughout the environment and enter the aquatic ecosystem. The major route of insecticides to water ecosystems in urban areas is through rainfall runoff and atmospheric deposition. Another source of water contamination by insecticides is from municipal and industrial dischargers. Most insecticides ultimately find their way into rivers, lakes and ponds (Tarahi Tabrizi, 2001; Honarpajouh, 2003; Bagheri, 2007; Shayeghi et al., 2007; Vryzas et al., 2009; Werimo et al., 2009; Arjmandi et al., 2010) and have been found to be highly toxic to non-target organisms that inhabit natural environments close to agricultural fields. The contamination of surface waters by insecticides is known to have ill effects on the growth, survival and reproduction of aquatic animals. In the past few years, the increase of mortality among the fish in various streams, lakes and ponds of around the world has drawn scholars’ attention to the problems caused by insecticides and pesticides runoff associated with intense agricultural practices. Different concentrations of insecticides are present in many types of wastewater and numerous studies have found them to be toxic to aquatic organisms especially fish species (Talebi, 1998; Uner et al., 2006; Banaee et al., 2008). Fishes are particularly sensitive to the environmental contamination of water. Hence, pollutants such as insecticides may significantly damage certain physiological and biochemical processes when they enter into the organs of fishes (John, 2007; Banaee et al., 2011). Authors found out that different kinds of insecticides can cause serious impairment to physiological and health status of fishes (Begum, 2004; Monteiro et al., 2006; Siang et al., 2007; Banaee et al., 2009). Since fishes are important sources of proteins and lipids for humans and domestic animals, so health of fishes is very important for human beings. Recently, many studies have been conducted to determine the mechanisms of insecticides in fishes, with the ultimate goal of