At the current stage of development, pond aquaculture in Ukraine is characterized by the comprehensive application of scientific approaches to fish breeding and rearing. Each breed of Ukrainian carp is differentiated by its structure, aimed both at maintaining its productive characteristics and preserving a specific gene pool. This enables the active use of industrial hybridization methods in the development of domestic carp farming, thereby increasing growth rates and enhancing the resistance of farmed fish to diseases and environmental factors. Comprehensive studies of the physiological, biochemical, and genetic characteristics of parental forms and their resulting hybrids reveal improvements in viability and productivity, or refute such effects, thereby enabling effective hybridization within the existing gene pool of Ukrainian carp. Proteins are among the key factors in metabolism, primarily due to their structural, catalytic, and regulatory functions. Considering this, reciprocal crossing of the Galician and the new, small-scale Lebedyn factory line of intrabreed Ukrainian carp breeds was carried out, resulting in first-generation hybrids. The cultivation of two-year-old fish of the studied carp groups was performed in polyculture with herbivorous fish species at a stocking density of 1,500 individuals per hectare. Fish rearing was conducted using a semi-intensive technology, with artificial feed provided from the second decade of July to mid-September. For feeding two-year-old fish, a complex diet was used, including artificial feeds and cereal-based feed mixtures containing soybean and sunflower meal, with a protein content of at least 26%. Subsequently, studies of certain physiological and biochemical parameters were carried out in the blood, skeletal muscle tissues, and liver of these hybrid carp. In particular, the concentrations of protein in blood serum, liver, and skeletal muscle, as well as the ratios of individual protein fractions in these tissues, were determined. The albumin-globulin ratio was also evaluated. Hemoglobin content and erythrocyte count were determined for the studied fish groups. To minimize the influence of exogenous factors on the studied parameters, all fish groups were reared under identical conditions, with hydrochemical and temperature regimes monitored throughout the entire vegetation period.
