TOTAL LEUKOCYTE COUNTS IN FISHES BY DIRECT OR INDIRECT METHODS?

Abstract

Several methods have been recommended or adapted to count total leukocytes in fishes, but the efficiency of diluents used in these methods are questioned. In this trial, total leukocyte count of Piaractus mesopotamicus Holmberg, 1887 (Characidae) was evaluated using three different methods, one direct and two indirect. The mean values of leukocyte counts by indirect methods were not statistically different (P>0.05). However, these values were higher than those resulting from the direct method (recommended by NATT and HERRICK, 1952). The low values obtained by the latter may be due to inefficient staining of leukocytes in the hemocytometer. Further studies are required for resolving this question. Therefore, fish hematology researchers must direct their efforts to find a methodology that allows accurate total leukocyte counting.