Comparison of Giemsa, Leishman, and Leishman-Giemsa Staining Methods for Evaluating Fish Blood Smears

Background: The hematological panel provides valuable information about the physiologic status and health of fish in aquatic environments through optimal staining of the nucleus, cytoplasm, and cytoplasmic granules. Objectives: Our research focused on creating a new Leishman-Giemsa dye mixture specifically for fish blood smears and evaluating its effectiveness compared to standard staining techniques. Methods: Blood samples were taken from 20 healthy common carp to produce three groups of peripheral blood smears: One for Leishman-Giemsa dye and two for Leishman’s and Giemsa’s stains. Two experienced clinical pathologists extensively examined all three types of blood smears based on four staining characteristics: Nuclear characteristics of erythrocytes and leukocytes, cytoplasmic characteristics, and leukocyte granulation. The mean ratings from the two experts for each staining technique were compared. Results: Regarding the characteristics of RBC and WBC nuclei, the two conventional staining methods, Leishman and Giemsa, yielded substantially lower mean scores than the new Leishman-Giemsa staining method (P<0.05). Leishman-Giemsa staining enhanced the clarity of RBC and WBC nuclear characteristics. The new Leishman-Giemsa staining technique resulted in a statistically significant (P<0.05) difference in the cytoplasmic characteristics of fish WBC compared to the other two methods. Conclusion: The results of this study demonstrated for the first time that fish blood cells stained with the novel Leishman-Giemsa method are more desirable. In addition, its nuclear and cytoplasmic staining is superior to that of conventional Giemsa and Leishman stains when used separately. The Leishman-Giemsa cocktail has a high index for air-dried smear discoloration.