Hematological Parameters of One-Year-Old (Fingerlings) Carp Fish

Background: The rapid intensification of aquaculture systems has heightened concerns regarding fish health and welfare, particularly in economically important species like the common carp (Cyprinus carpio). Hematological parameters serve as sensitive indicators of physiological status, making them essential for evaluating the effects of rearing technologies and environmental conditions on fish health.  Aims: The aim of this study was to evaluate the hematological parameters of one-year-old carp (fingerlings) reared under different aquaculture conditions and to identify the influence of these conditions on fish physiological status. Study Design:  Experimental comparative study. Place and Duration of Study: The research was conducted at the “Oq Amur” fish farm, Uzbekistan, during the production cycle of one-year-old carp. Methodology: Fish were divided into five groups according to rearing conditions: extensive technology, intensive technology, artificial pond, tank system, and recirculating aquaculture system. Blood samples were collected from the caudal artery using sterile syringes. Hematological parameters including hemoglobin concentration, erythrocyte count, leukocyte count, hematocrit, mean corpuscular hemoglobin (MCH), and mean corpuscular volume (MCV) were determined using standard laboratory methods and analyzed statistically. Results: Significant variations in hematological parameters were observed depending on rearing conditions. The highest hemoglobin level was recorded in artificial ponds (89.88 ± 4.03 g/L), while the lowest was observed in recirculating systems (60.56 ± 4.32 g/L). Erythrocyte counts ranged from 1.5 ± 0.04 × 10¹²/L in extensive systems to 1.0 ± 0.056 × 10¹²/L in recirculating systems. Hematocrit values decreased from 39.7 ± 2.12% to 30.7 ± 2.17% across these systems. In contrast, leukocyte counts were highest in recirculating systems (52.9 ± 0.2 × 10¹²/L). Variations in MCH and MCV values also reflected differences in environmental and technological conditions. Conclusion: Rearing conditions significantly affect the hematological status of carp. Artificial pond systems provide more favorable physiological conditions, whereas recirculating systems may induce stress-related changes. These findings are important for optimizing aquaculture practices and improving fish health management.