Metabolic effects of naphthalene, toluene or phenol intoxication in the cichlid fish tilapia, Oreochromis mossambicus: Changes in aminotrasferase activities

Exposure of the cichlid fish tilapia, Oreochromis mossambicus, to acutely stressful (96-h LC₅₀) levels of naphthalene, toluene or phenol for 4 days did not produce any change in the activities of aspartate and alanine aminotransferases in liver or muscle. However, the stress of 10 weeks exposure to chronically sublethal (50% 24-h LC₅₀) concentrations of the hydrocarbons stimulated the enzyme activities in both the tissues. This change was accompanied in some groups by reduced tissue levels of soluble proteins and free amino acids, suggesting increased tissue proteolysis in these sublethally stressed tilapia.