COMPARATIVE ANALYSIS OF THE EFFECT OF HORMONE-INDUCED STRESS ON HEMOSTASIS IN THE CYPRINUS CARPIO AND THE OREOCHROMIS NILOTICUS

Background: The mortality of freshwater fish due to stress during various production manipulations is a severe problem, which requires a thorough understanding of the basic mechanisms involved, including the hemostasis system. Therefore, on the application level, the study of blood clotting can perform fish coagulopathies diagnostics and develop practical preventive and therapeutic anticoagulation methods for fish farming. Aim: The goal of this research was a comparative assessment of the reaction of some hemostasis parameters of two commercial fish species, carp Cyprinus carpio and tilapia Oreochromis niloticus, to the stress of different duration induced by corticosteroids. Methods: The fishes were divided into three groups: chronically stressed (induction by betamethasone), acutely stressed (induction by dexamethasone), and control animals with blood taken from the caudal hemal canal before hormone treatment(by dexamethasone and betamethasone), then 7 and 21 days after. Results and Discussion: Changes in the following parameters were studied: thrombin time, prothrombin time, activated partial thromboplastin time, the concentration of fibrinogen, soluble fibrin monomer complexes, antithrombin. It was found that both hormone-induced stress and handling stress associated with blood sampling strongly increased blood clotting ability in carps (prothrombin time decrease by 78,5-86,1%, fibrinogen increase by 12,7-100%, thrombin time decrease by 83,4-85%, and antithrombin III decreases by 15,3-21,7%), while in tilapias, acceleration of blood clotting by intrinsic and extrinsic pathways were recorded by the end of the experiment only in fishes with imitation of chronic stress (prothrombin time decrease by 76,8%, activated partial thromboplastin time decrease by 20,0%, and 2,3 multiplying soluble fibrin monomer complexes). Conclusions: It was concluded that the adaptive mechanisms of the tilapia (Oreochromis niloticus) organism allowed the clotting function to recover in most cases by the end of the experiment in all groups of fish, in contrast to carps (Cyprinus carpio).