The effect of one intraperitoneal injection of 1.33 ml of CCI, per kg of fish was studied. Two experimental series were performed and studied for 10 days (with diluent) and 24 h (pure CCl,) periods. LDH, GOT, GPT, GR, GDH, CPK, G-&Pase, and AlkPase were studied. The activity of all enzymes in blood increased: LDH (four times the control), GOT (two times), GPT (three times); they reached a maximal activity 12 h after injection of diluted CCI,. The levels of some enzymes were also examined in the liver. With pure CCI4, maximal enzyme activity in blood occurred earlier (6 h). A 6 to 10 times increase was observed for GOT, GPT, LDH, GR, and GDH. Histopathological observations were correlated with these enzymes studies.An Aerornonas disease characterized by the destruction of the dermis, the exposure of the muscle, and by the presence of numerous petechiae in the liver enabled us to examine the relationships between naturally induced tissue damage and enzyme levels in blood. The levels of seven blood enzymes were determined and the most significant modifications were observed for LDH and CPK which increased their concentration from 3 to 7 times respectively. A pyruvate saturation test demonstrated that LDH was probably from liver as it was observed after CCI, poisoning. The contribution of such biochemical studies in fish research is evaluated.

This paper describes the determination in rainbow trout of the normal levels in the plasma of eight enzymes known to be significant in animal pathology. Some relationships between plasma enzyme levels and the enzyme activities in selected tissues are discussed. For LDH which is ubiquitously distributed, we chose, by way of saturation tests, the optimum concentrations of pyruvate and NAUH in the assay medium. The LDH isoenzyme ratio ' was determined for heart tissue, liver, and white muscle. When blood was withdrawn from caudal vessels, we observed a net increase of plasma enzyme activities, mainly of CPK and LDH, which was demonstrated to originate from surrounding muscle. 'Thus cardiac sampling was thc only suitable way of obtaining blood for this kind of study. Slightly haemolyzed blood appearcd suitable for enzyme determinations except for AlkPase which is about 50 times more concentrated in erythrocytes than in plasma. CPK was highly eoncentratcd in the heart and the muscle, GOT was concentrated in the heart while the liver appeared lo be a valuable source of GDH (as well as the kidney) and GPT.