Toxicity of intraperitoneally injected ivermectin in sea bream, Sparus aurata

Ivermectin has been widely used as a treatment against sea lice infections of farmed fish (salmonids and nonsalmonids) without any official license for use in aquaculture. This study presents data on the toxic side effects of ivermectin administered intraperitoneally in sea bream, Sparus aurata at single doses of 100, 200, 400 and 800 mug g ivermectin kg 1 fish. The toxicity of ivermectin was evaluated for a period of 35 days post treatment by determining changes in selected hematological parameters (hematocrit, hemoglobin, red blood cell count, leucocyte count, differential white blood cell count, plasma glucose, electrolytes, urea and alkaline phosphatase), pathological effects in the tissues and the organs of the fish using histological techniques and changes in the behavior of the fish. The results showed a decrease of the hematocrit value one hour after the injection for most of the doses along with an increase of the hemoglobin concentration, the number of the white blood cells, the lymphocytes and monocytes and plasma glucose. No mortality or any histopathological alteration at the tissues examined, were recorded. The fish, which were injected with the highest dose of ivermectin, experienced a loss of appetite, lethargy and darkening of their color during the first week post injection. All the studied parameters reached the normal level by the end of the experiment indicating a low and reversible toxicity of the drug.