Effect of Short Term Exposure of Ethoxyquin on Hematological Parameters in Fresh Water Fish, Oreochromis mossambicus.

Abstract

Ethoxyquin (EQ, 6-ethoxy-1,2-dihydro-2,2,4-trimethylquinoline) is a synthetic antioxidant that is included in  fish feeds in order to protect it against lipid peroxidation. Many unfavourable side-effects have been observed in animals fed with EQ-containing feeds. Studies on the harmful effects of EQ on vertebrates are growing, but the effects of EQ in aquatic systems have rarely been described. In the present study LC₅₀ 96 hr value of EQ to the freshwater fish Oreochromis mossambicus (Thilapia) was determined through Probit analysis.The bioassay found that the median lethal dosage in fish after 96 hours (LC50-96h) was 11.37 mg/L. The fish were reared in sublethal concentration of the chemical for 24hr, 48hr, 72hr and 96hr. Blood was taken from the treated and control fish and haematological parameters were analyzed. It was found in the present study that RBC count and hemoglobin values in fish decreased significantly as a result of EQ application. Such a situation can be an indicator for haemolytic anemia. An increase in white blood cells was noticed, which probably represent an adaptive response to help the organism to counteract the toxic effects of EQ. A significant increase in neutrophil count was noticed suggesting that the fish is trying to overcome the toxic effect of chemicals by leukocytosis mechanism.