The numbers of leukocytes and thrombocytes are considered
important indicators of fish health. In this study, the fish reared at
the low stocking density and fed the probiotic-supplemented diet
showed higher values of thrombocytes compared with the fish fed
the control diet and raised at the same stocking density. The consumption
of the probiotic diet induces the production of thrombocytes
when these fish are raised at a low stocking density, which
may be interesting because these cells play an important role in the
immune system [45]. The phagocytic ability of thrombocytes for
different substances (bacteria and other antigens) in teleosts has
been reported by Burrows [46], Stosik [47], and Kolman [48].