Factors Affecting Hematological Indices in Free-living Fish Populations

Abstract

L u sko v:i. V.: Factors Affecting Haematological Indices in Free-living Fish Populations. Acta vet. Bmo 1998,67: 249-255. The values of physiological indices in fish blood are significantly affected by a complex of factors. Since fishes are poikilothermic, this complex includes the influence of both biological and environmental factors. For a correct interpretation of the observed values of the various haematological indices. the knowledge and consideration is required of the most significant factors that may affect the collection, treatment and, above all. evaluation of data. In investigations of 2 - 3 annual cycles of selected indices in the blood of adults of Salmo trulla m.jario. Thymallus thymallus, Chondrostoma nasus, and partial cycles of Leueiscus cephalus and Barbus barblls. I evaluated the most important, generally occurring influences affecting their values. With respect to the rather high individual variability, values obtained from a group sample of fish should be employed on principle. One should also respect the seasonal variation in any index under study. as well as the sex of the fish, which significantly affects some of the indices (HC. HB, AST). Spawning appears to be a so-called major factor that significantly affects, above all. the values of biochemical indices. It is highly desirable to use identical procedures and standard methods in determining the values of haematological and biochemical indices in fish blood.