Sub-Lethal Effects of Herbicide Paraquat on Hematological Parameters of Benny Fish Mesopotamichthys Sharpeyi Alireza Safahieh 1 , Yaqub Jaddi 1 , Vahid Yavari 2 and Reza Saligheh Zadeh 2 1 Department of marine biology, Faculty of Marine Sciences and Oceanography, Khoramshahr University of Marine Science and Tehnology, Khoramshahr, Iran. 2 Department of fisheries, Faculty of Marine Natural Resources, , Khoramshahr University of Marine Science and TehnologyKhoram, shahr, Iran. Abstract. Pesticides may appear as environmental contaminants once they enter aquatic ecosystem after using in agriculture. Less degradable compounds may even enter aquatic food chains and cause health problems for aquatic organisms and sometimes for human. Paraquat is a chlorinated herbicide which usually is used in agriculture fields in the northern part of Iran. In this area is the main habitat for benny fish in Iran and fish culture (particularly benny fish) is practiced there. To study the toxicity of paraquat on some hematological parameters of benny fish, 40 individuals were devided into 4 groups and each groups was acutely exposed to paraquat concentrations of 0.37, 0.74 and 1.11 mg/l (equal to 25, 50 and 75 percent LC 50 96h respectively). After 96 h exposure fish were taken from aquariums, the blood samples were prepared and their hematological parameters including erythrocyte (RBCs) and leukocyte (WBCs) counts, hemoglobin concentration (Hb), hematocrit (Hct) and blood indices (MCV and MCH) were studied. Results showed that paraquat significantly reduced all studied parameters (P<0.05), while the percentage of reduction was proportional with paraquat concentrations. It is suggested that paraquat exposure might produces adverse effect on blood parameters of fish which results in anemia. This condition may affect normal growth, reproduction, immunity and survival of fish in both natural and culture conditions. It is recommended that farmers replace paraquat by less harmful and more degradable herbicides. Keywords: Paraquat, Toxicity, Heamatology, Mesopotamichthys sharpeyi. 1. Introduction Population increase together with limitation in agriculture lands have significantly increased the need for using of herbicides in agriculture [1]. Though agriculture products have been greatly depended on using of herbicides to control unwanted plant and weeds, however they may endanger other organisms specially when they rich to aquatic environment [2]. Floods and run off could dissolve applied herbicides and shift them into the rivers or seas. Aquatic animals may uptake herbicide from surrounding medium by different routs as non- target organisms. Non biodegradable compounds even can enter food chains and affect people who consume contaminated foods. Producing toxic effects for animals like fish is another impact of herbicides in aquatic environment. Paraquat is an organochlorine herbicide which is widely used in southern part of Iran where the largest fresh water system is located [3]. Among local fishes, Benny Mesopotamichthys sharpeyi (Günther, 1874) is dominant and occupies an important position in people diet. It is successfully cultured in aquaculture [4]. Previously some studies have been conducted to investigate the toxic effects of some pesticides on hematological parameters of fishes particularly on cold water species [5, 6]. However the effects of paraquat on benny fish are not well understood. This study was carried out to investigate toxicity of paraquat on hematological parameters of Mesopotamichthys sharpeyi. 2. Materials and Methods 2012 2nd International Conference on Biotechnology and Environment Management IPCBEE vol.42 (2012) © (2012) IACSIT Press, Singapore DOI: 10.7763/IPCBEE. 2012. V42. 27 141