Pesticides are environmental contaminants that after use in agriculture, aquatic ecosystems are entered. These contaminants can enter the food chain and can cause problems for aquatic organisms and even humans. During the acute toxicity of this herbicide paraquat on some blood parameters, Mesopotamichthys sharpeyi (the total number of red blood cells, hemoglobin concentration, and total white blood cell count, hematocrit and blood indices) in fisheries laboratories, Khorramshahr University of Marine Science and Technology were studied. The sub lethal toxicity studies of 40 fish in 4 treated on the basis of three different treatments LC 50 96 h (25, 50 and 75 percent LC 50 96 h), and a control treatment for 96 hours were exposed to the pesticides paraquat. 10 fish were randomly distributed into plastic containers 25 liters. Tests based on standard methods O.E.C.D were on the fish and the static. The number of red blood cells, hemoglobin concentration, percent hematocrit, white blood cell count, MCV, MCH and MCHC Mesopotamichthys sharpeyi at different concentrations after 96 h with the control treatment significantly reduced (0.05 > P) that was directly affected by different concentrations of the paraquat.