The levels of ornithine carbamyl transferase, acid phosphatase, alkaline phosphatase, leucine amino peptidase, creatine kinase, amylase, glutamic oxalacetic transaminase, glutamic pyruvic transaminase, lactate deshydrogenase, hydroxybutyrate deshydrogenase, glutamate deshydrogenase and malate deshydrogenase were determined in the plasma of Rainbow Trout and Tench submitted to water temperature increases. In the Rainbow Trout a thermal shock from 12 to 21 degrees, increases activities of some enzymes while temperature increase up to pre-mortem stage causes very important changes in enzymatic levels. In the Tench a thermal shock from 12 to 28 degrees causes more changes of enzymatic activities than a shock from 12 to 25 degrees. In Tench acclimated to 25 degrees, various enzyme levels are increased in comparison with 12 degrees control animals. A high potassium level in water causes complex changes in enzyme levels. The most sensitive enzymes to thermal disturbance are GOT and GPt transaminases which increase whatever the aggression form, amylase when thermal disturbance is moderate, alkaline phosphatase and malate deshydrogenase in case of strong thermal stress. The study of these enzymes is recommended for watching the state of fishes living in artificially heated waters.
