Biochemical stress responses in tissues of the cichlid fish Cichlasoma dimerus exposed to a commercial formulation of endosulfan.

Median lethal concentration (LC(50)) and sublethal effects of the commercial endosulfan formulation Zebra Ciagro(®) on the fish Cichlasoma dimerus were studied. The 96-h LC(50) was estimated as 17.7 µg/L. In order to investigate sublethal effects, fish were exposed to 25% and 50% LC(1) (3.4 and 6.8 µg/L, respectively). Endosulfan (ED) significantly increased the hemoglobin concentration and white blood cell count after 96 h. Differential leukocytes count was also altered, due to an increase in the percentage of neutrophils in exposed fish. The hepatopancreatic tissue of fish under ED treatment showed a decrease in aspartate aminotransferase and alanine aminotransferase and an increase in alkaline phosphatase. Lipid peroxidation levels in the 6.8-µg/L ED-containing group were higher than those in control fish for all organs tested (gills, hepatopancreas, and brain).