en Acute Toxicity and Behavioral Changes of the Gold Fish (Carassius Auratus) Exposed to Malathion and Hinosan تخصصي Special پژوهشي Research <b>Background: </b>Pesticides are widely used in agriculture. Excessive use of pesticides has health risk for human and threatens non-target organisms. This research aimed to determine lethal concentrations of malathion and Hinosan for Carassius auratus (5±1 gr) [mean ± SD]. <br><b>Methods:</b> Experiments were performed according to O.E.C.D for 4 days (96 h) and concentrations of 0, 1, 2, 4, 8 mg L-1 Hinosan and 0, 1, 2, 4, 16 mg L-1 malathion with three replicates. LC1, LC10, LC30, LC50, LC70, LC90 and LC99 for 24, 48, 72 and 96 h were determined using a probit analysis. <br> <b>Results: </b>The results indicated that the 96 h LC50 value of Hinosan and malathion for Gold fish was 4.02 and 4.71 mg/L, respectively. Fishes exhibited irregular, erratic and darting swimming movements, hyper excitability, bruise in the caudal section, loss of equilibrium and sinking to the bottom. <br><b>Conclusion: </b>Malathion and Hinosan have medium toxicity for C. auratus and could cause irreversible harm and behavioral changes. Carassius auratus, Hinosan, LC50, Malathion. Carassius auratus, Hinosan, LC50, Malathion. 1203 1208 http://ijt.arakmu.ac.ir/browse.php?a_code=A-10-2-176&slc_lang=en&sid=1 Saeid Shahbazi Naserabad سعید شهبازی نصرآبادی saeid.shahbazi@ut.ac.ir 10031947532846003891 10031947532846003891 Yes Department of Fisheries, University of Tehran, Karaj, Iran. Department of Fisheries, University of Tehran, Karaj, Iran. Alireza Mirvaghefi علیرضا میرواقفی 10031947532846003892 10031947532846003892 No Department of Fisheries, University of Tehran, Karaj, Iran. Department of Fisheries, University of Tehran, Karaj, Iran. Mohammad Hasan Gerami محمدحسن گرامی 10031947532846003893 10031947532846003893 No Department of Fisheries, University of Gonbad Kavous, Golestan, Iran. Department of Fisheries, University of Gonbad Kavous, Golestan, Iran. Hamed Ghafari Farsani حامد غفاری فارسانی 10031947532846003894 10031947532846003894 No Department of Fisheries, University of Tehran, Karaj, Iran. Department of Fisheries, University of Tehran, Karaj, Iran.