Hematology is an important pathological and diagnostic tool. This paper describes the hematological parameters of 76 specimens of Hoplias malabaricus infested with monogenean parasites, which were collected from two lagoons. The hematological parameters included: erythrocyte count (Er), microhematocrit (Hct), hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC). The blood parameters showed no significant changes associated with the infestation. Water temperature was found to be negatively correlated with MCV and Hct, with values of rs= −0.52, p<0.0001 and rs= −0.48, p<0.0001, respectively. The mean Relative Condition Factor was Kn=1.01, indicating good health conditions of the fish in these lagoons. No correlation was found between the monogenean infestation and the blood parameters, or between the environmental factors and the monogeneans.
Parasites; blood cells; freshwater fish