Haematological values of paiche, Arapaima gigas, were determined in 120 blood samples collected from May 2009 to January 2011. The fishes were cultivated in two fish farms located in the province of Maynas, Loreto, Peru. Blood samples were classified according to four age groups: 10-30, 31-180, 181-365 and >365 days. Data for erythrocyte and leukocyte counts, haemoglobin, haematocrit and differential leukocyte count were obtained. Red cell count and haemoglobin increased with age (p<0.05).