Common Carp (Cyprinus carpio) Blood Cells in Hayem's Solution – Stable or Not?

A haematological analysis is commonly used in studies concerning fish, e.g.to evaluate the influence of various environmental factors on the physiological state of a population. Furthermore, a manual haematology is still used for conducting fish blood analyses. The aim of the current study was to determine how long after the procedure of blood collection in common carp (Cyprinus carpio) the samples diluted with Hayem's solution would provide results for the red blood cell and white blood cell counts with no significant changes. The blood was taken from 15 healthy individuals and diluted with Hayem's solution immediately after the collection procedure. Next, an erythrocyte count and leukocyte count were performed. The counts were repeated after 1, 2, 3, 5, 9, 16 and 23 days. The results of the current study indicate that the erythrocyte count should be performed within a maximum of 16 days (or better within 9 days) after the sample preparation, while the leukocyte count should be conducted within 2 days.