WEIGHT-LENGTH RELATIONSHIP AND BLOOD CHARACTERISTICS OF SILVER AROWANA, A OSTEOGLOSSIDAE FROM THE STATE OF AMAPÁ (BRAZIL)

Abstract

This study investigated the weight-length relationship, plasma biochemical and hematological parameters in Osteoglossum bicirrhosum from the Preto River, in the State of Amapá (Brazil). The weightlength relationship showed a negative allometric growth, with the value of the regression constant (b) equal to 2.539. The relative condition factor (1.00 ± 0.02) indicated good body conditions of fish in their natural environment. In the blood smears of O. bicirrhosum (616.2 ± 209.1 g), erythrocytes, thrombocytes and leukocytes were found with morphological characteristics similar to those of other Brazilian fish. Mean glucose levels were: 46.5 ± 14.6 mg dL^-1 (27.1-95.8); total protein 4.2 ± 0.6 g dL^-1 (2.3-5.3); total cholesterol 303.9 ± 140.4 mg dL^-1 (81.6-718.4); triglycerides 244.8 ± 57.5 mg dL^-1 (76.2-361.9); total erythrocytes 2.75 ± 0.37 x 106 μL^-1 (1.940-3.350); hemoglobin 8.8 ± 1.2 g dL^-1 (6.3- 13.0); hematocrit 26.6 ± 2.3% (21.0-32.0); mean corpuscular volume 98.6 ± 15.8 fL^-1 (72.4-149.5); mean corpuscular hemoglobin concentration 32.9 ± 3.9 g dL^-1 (23.4-44.8); total thrombocytes 90,816 ± 58,888 μL^-1 (14,760-210,250); total leukocytes 75,287 ± 34,546 μL^-1 (10,290-191,475); lymphocytes 72,555 ± 33,046 μL^-1 (10,084-181,901) and 96.5 ± 2.5%(87-100); monocytes 1734 ± 1683 μL^-1 (0- 7.308) and 2.3 ± 1.8% (0-7); neutrophils 915 ± 1435 μL^-1 (0-6.518) and 1.1 ± 1.5% (0-7), eosinophils 63 ± 225 μL^-1 (0-960) and 0.1 ± 0.3% (0-1). Therefore, lymphocytes were the predominant leukocytes, while eosinophils were the least frequent. This was the first report of leukocytes and biochemical parameters for O. bicirrhosum. Lastly, it was established reference blood values that can be used as interpretative data obtained for this species when under similar environmental conditions.