[Comparative evaluation of carbohydrate metabolism in perch (Perca fluviatilis L.) from water bodies with different contents of humic acids].

Characteristic features of energy metabolism, related to the adaptation of fish to adverse environmental conditions, were detected in perch (Perca fluviatilis L.) inhabiting the lake with a high humus content, compared to perch from the control lake. We studied a complex of enzymes involved in carbohydrate metabolism and assessed the relationship between metabolic pathways using correlation analysis. The intensity of oxidative metabolism was greater in the gulls. The activation of energy metabolism in the liver was characterized by an increased consumption of carbohydrates. In addition, the role of the liver-specific lactate dehydrogenase (LDH) isoform D4 also increased. The activity of enzymes involved in carbohydrate metabolism decreased most strongly in white skeletal muscles, whereas the role of the pentose-phosphate pathway (along with glycolysis) in the production of muscle lactate increased. The adaptation of fish to a high-humus aquatic environment was accompanied by a slight decrease in their fatness.